Shellfish Tortellini with Lobster, King Prawn and Vermouth Beurre Blanc

This is the plate you build a menu around — three glossy tortellini, each one full of sweet lobster and prawn bound in a silky shellfish mousseline, sitting in a pool of vermouth beurre blanc reinforced with a reduced shellfish stock. It borrows its shape and ambition from the tasting-menu tortelli you see at two-star restaurants, but everything here is doable at home across an afternoon. The sauce does most of the heavy lifting, so the pasta can stay almost naked — just good dough, clean shellfish, and a glossy, French-leaning butter sauce with enough vermouth to keep it interesting.

How to cook

This is a project plate with three main components — dough, filling, and sauce — and the magic is in the sequencing. Make the pasta dough first so it has time to rest. While it rests, cook the lobster, peel the prawns, and use every bit of shell to build a shellfish stock. The mousseline and filling come together while the stock reduces. Shape the tortellini, then make the beurre blanc right before service — this is one of those sauces that rewards being fresh and punishes anyone who tries to reheat it. Budget about two and a half hours start to finish and you’ll move through it without rushing.

Start with the dough. The high yolk ratio — six yolks to two whole eggs — gives you a rich, golden dough with enough fat to roll ultra-thin without tearing, which you need for filled pasta. Mound the 00 flour (300g) on a clean wooden or marble surface and make a wide, deep well in the centre. Crack in the yolks and whole eggs, add the olive oil and salt, and whisk with a fork while gradually pulling flour in from the walls. Once you have a shaggy mass, knead on a lightly floured surface for 8-10 minutes until it’s smooth, elastic, and slightly tacky — not sticky, not dry. A properly kneaded dough springs back slowly when you press it. Wrap it tightly in cling film and leave it to rest at room temperature for at least 45 minutes. Skip this rest and the dough will fight you all the way through the roller.

Now the lobster. Bring a large pot of heavily salted water to a rolling boil, drop the live lobster (1) in head-first, and cook for exactly 4 minutes for a 500-600g specimen — you want it barely set, because it will cook again inside the pasta. Lift it out and plunge straight into a bowl of iced water to stop the carryover. Once cold, twist off the tail and claws, crack the shells with the back of a heavy knife or kitchen shears, and ease the meat out in whole pieces. Cooked lobster meat is fragile — work gently, keep it cool, and save every piece of shell, including the body carcass.

Peel the king prawns (6) and reserve every scrap of head and shell — the heads are where the flavour lives. Devein by running the tip of a paring knife down the back of each prawn and flicking out the dark line. Dice all the lobster meat and 4 of the prawns into 5mm cubes — small enough that they’ll distribute evenly through the filling but still give you a real bite of shellfish. Keep the remaining 2 raw prawns back for the mousseline and chill everything.

The shellfish stock is the secret weapon in this dish — it’s what gives the beurre blanc its backbone and keeps the sauce tasting like the sea rather than just like butter. Heat the olive oil (2 tablespoons) in a wide saucepan over medium-high heat and tip in every scrap of shell — lobster tail, claws, body cavity, and all the prawn heads and shells. Press down on them with a wooden spoon as they sizzle to crack them further and release their oils. You’ll see the shells turn a deep coral and the kitchen will start to smell intensely of the sea. This takes 4-5 minutes of patient sizzling.

Stir in the tomato paste (1 tablespoon) and cook for a minute until it turns brick-red and loses its raw tinny edge. Add the chopped shallot, carrot, celery and smashed garlic and cook for another 4-5 minutes until the vegetables soften. Pour in the cognac (2 tablespoons) — if you’re comfortable, tilt the pan towards the gas flame to flambé, otherwise just let it cook off for 30 seconds — then add the white wine (100ml) and reduce by half. Pour in the water or light fish stock (600ml), add the bay leaf, parsley stems and peppercorns, and bring to a bare simmer.

From here, patience. Cook the stock gently for 40 minutes — the surface should barely move, just a few lazy bubbles at a time. A hard boil emulsifies the shellfish fat into the water and gives you a cloudy, greasy stock. Gentle simmer only. After 40 minutes, strain through a fine sieve, pressing hard on the shells with a ladle to extract every drop, then pass it through a coffee filter or a double layer of muslin for clarity. Return the strained liquid to a wide pan and reduce it hard over high heat to about 120ml of concentrated shellfish essence — it should taste almost painfully intense on its own. This reduction is the flavour foundation of the sauce.

For the filling, you’re making a classical mousseline — a French trick where raw fish, egg white and cream are blitzed and emulsified into a silky paste that sets beautifully when poached, binding the diced shellfish without weighing it down. Every ingredient needs to be cold, because the cream emulsifies into the protein only if the mixture stays below about 10°C — if it warms up, it splits. Put the cold cod (80g) and the 2 reserved raw king prawns into a food processor with the cold egg white and a good pinch of salt. Blitz to a smooth paste, scraping down the sides, then with the motor running, stream in the cold double cream (80ml) in a thin, steady pour. The mixture will thicken into a glossy, ribbon-like paste. Stop the moment it’s smooth — if you keep going, the fat will break out and you’ll have a grainy mess. For a textbook finish, push the mousseline through a fine sieve with a rubber spatula; it takes three minutes and makes the filling feel like silk.

Fold the diced lobster and prawn meat into the mousseline along with the lemon zest, chives and tarragon. Season carefully with salt and white pepper — and this matters. Poach a small blob (about a teaspoon) in a pan of simmering water for a minute, then taste it. It should taste clean, briny, sweet, and distinctly of shellfish, with a gentle herbal lift from the tarragon. Adjust the main batch accordingly — an under-seasoned filling disappears under the buttery sauce, so err on the bold side. Chill the filling for at least 20 minutes until it firms up enough to shape cleanly.

Now the tortellini. Divide the rested dough into 4 pieces and keep three wrapped at all times — pasta dough dries out fast. Flatten the first piece with your palms, pass it through the widest setting of a pasta machine, fold into thirds, then pass through again a couple of times to strengthen the sheet. Begin rolling through progressively thinner settings, one step at a time, until you reach the second-to-last setting. The sheet should be almost translucent — hold it up to a light and you should just about see the shadow of your hand through it.

Lay the sheet flat on a lightly floured surface and cut into 7cm squares. Place a heaped teaspoon of filling (about 15g) in the centre of each square. Brush two adjacent edges with beaten egg, then fold the square in half diagonally to form a triangle, pressing gently around the filling to push every bit of air out — trapped air is the single biggest reason tortellini burst in the water. Now shape: wrap the long edge of the triangle around your fingertip so the two outer points meet, pinch them firmly together, and curl the peak of the triangle up. You should have a little ring-shaped parcel with a peak rising from the top. The first two will look rough; by the fifth you’ll have the hang of it. Aim for 12 tortellini, three per plate.

Now the beurre blanc, which is the soul of this dish. In a small saucepan, combine the finely diced shallots (2 small), vermouth (100ml), white wine (50ml) and white wine vinegar (1 tablespoon). Simmer over medium heat until the liquid has reduced to about 2 tablespoons of syrupy, intensely flavoured reduction — this takes 6-8 minutes. The vermouth brings herbal, bittersweet notes that plain wine can’t, and Noilly Prat is the gold standard here because of its dry, resinous character. Pour in the reduced shellfish stock (120ml) and the cream (50ml) — the cream is a stabiliser, making the sauce more forgiving without dulling the flavour — and reduce gently for 3-4 minutes until the mixture coats the back of a spoon.

Pull the pan off the heat and start mounting the butter. This is a classical beurre blanc move: whisk in the cold butter (150g) one or two cubes at a time, letting each piece emulsify before adding the next, over the lowest possible heat or just off the heat entirely. The sauce should turn from thin and translucent to glossy, opaque and velvety. Keep the pan moving and don’t let it boil at any point — if the sauce sees a rolling simmer, the butter breaks out and you’ll have a greasy puddle with no coming back. The ideal temperature is around 60-70°C. A kitchen thermometer takes the guesswork out of this and is worth having if you make sauces of this kind.

Finish the sauce with the lemon juice (1 teaspoon) and season carefully with fine salt — taste at every stage, as the reduction concentrates salt from the stock. Keep the finished beurre blanc warm by sitting the pan over a bowl or second pan of warm (not hot) water. This is a one-shot sauce — it doesn’t reheat, so time it to finish at the same moment the pasta is ready.

Bring a large pot of heavily salted water to a rolling boil — it should taste like seawater. Drop the tortellini in gently and cook for 3-4 minutes. They’re ready when they float and the pasta feels tender with a slight bite — the filling will be cooked through in that time. Lift them out with a spider, letting the water drain back, and slide them straight into a wide pan with the finishing butter (30g) and a splash of pasta water. Swirl for 20 seconds until the butter melts into a light glaze that clings to the pasta.

Bonus points

• Swap lobster for langoustine: Replace the lobster with 6-8 whole langoustines. Peel them raw, use the tails in the filling (no pre-cooking needed — the mousseline brings them through gently), and roast the heads and shells hard for the stock. Langoustine gives you a sweeter, more delicate flavour than lobster and is the version you’ll see in most French tasting menus.
• All-prawn version: If lobster isn’t an option, use 500g of large shell-on king prawns or tiger prawns total. Dice half the meat for the filling and blitz the rest (raw) with the cod and egg white for the mousseline — you get an even purer prawn flavour. The stock made from prawn heads and shells is almost as good as a lobster stock if you roast them hard first.
• Crab variation: Replace the lobster meat with 200g of fresh white crab meat, picked clean. Don’t cook it — just fold it into the mousseline at the end. Use crab shells in the stock alongside the prawn shells for a deeper, sweeter, slightly oceanic base.
• Bisque-style reinforcement: For an even richer sauce, blend a spoonful of the roasted shells with a little stock before straining, then push through the sieve. It intensifies the colour and body of the beurre blanc without overpowering it.
• Saffron variant: Bloom a small pinch of saffron (about 10 threads) in a tablespoon of warm water and whisk it into the finished beurre blanc. Turns the sauce a glowing amber-gold and adds a floral note that plays beautifully with shellfish.
• Finish with brown butter: Replace 30g of the cold butter in the beurre blanc with 30g of cooled brown butter (cooked until the milk solids turn hazelnut). The sauce picks up a toasty, nutty depth that pairs unreasonably well with prawns.
• Serve as a three-bite course: Plate just one single tortellino in the centre of a small warmed bowl with a spoonful of sauce — classic tasting-menu presentation and lets the filling really show off.

Serving

This is a dish made for composed plating. Warm your bowls first — a beurre blanc on a cold plate turns grainy within seconds, and you’ve worked too hard to lose it at the finish line. Use wide, shallow bowls with a deep well so the sauce pools rather than runs to the rim.

Spoon a generous pool of the beurre blanc into the centre of each bowl. Arrange three tortellini per bowl in a loose triangle, placing them so they sit partly above the sauce with just the bottoms submerged — you want the pleated tops on show. Scatter over the snipped chives and a few leaves of micro basil or pea shoots, and finish with the smallest pinch of flaky sea salt. Resist the urge to drizzle more sauce over the top; the tortellini should stand proud.

For wine, the natural partner is a dry Loire Chenin Blanc — a Savennières or aged Vouvray has the weight and waxy texture to match the butter and the acidity to cut it. A crisp Chablis (Premier Cru if you’re celebrating) is the safe move and works beautifully. For something more adventurous, try a dry, bone-dry Riesling from Alsace or a good white Côtes du Rhône with some Roussanne in the blend — both have enough body to stand up to the sauce without flattening the shellfish.