Heat the sous vide water bath to 60ºC.Steep the lobster in recently boiling water for 3 minutes. Remove it, and remove the claws and put them back in the hot water for a further five minutes. You might want to use rubber gloves or a towel, because the shellfish will be hot. While it’s still hot, twist off the tail. Twist off the end fan and push the tail meat out of the larger end. Cut in half and remove the digestive tract that goes up the length of the tail near the top, if present.After five minutes, remove the claws, crack them open using a nut cracker or similar tool, and extract the meat aiming to keep it as whole and undamaged as possible.If using sous vide, lightly season the flesh, and then place the tail meat in the sous vide pouch, add half the butter on top, add the rest of the meat and then more butter. Vacuum seal the pouch and put to one side.Remove the insides from the head, and then chop the shell up into medium-sized pieces. Heat the olive oil and sauté the shell over a medium high heat, stirring often, for five minutes or so. Then reduce the temperature to medium and add the onion, carrot and garlic. Fry these for a further few minutes until softened but not coloured. Then add the white wine, brandy, and the tomato purée. Simmer until the wine has been reduced by half.Add the boiling water and simmer for 25 minutes. Then strain the lobster sauce through a fine sieve into a clean pan. If you taste the liquid at this point, you’ll probably think it somewhat underwhelming, but panic not. Simmer this liquid until it has reduced down by around two-thirds. While that’s doing, sauté the leeks in a small frying pan with a little oil. When they’re nearly done, add the butter and continue to cook on a low heat.Also, put the new potatoes in to cook in a small pan of salted water. When the potatoes are soft, take them off the heat and lightly crush them with a fork or a potato masher. Put to one side.At this point, the flavour of the sauce should be a lot more powerful. Add the double cream and continue to simmer gently.While the sauce is thickening, put the lobster into the sous vide water bath for 8 minutes. If not using sous vide, add a couple of tablespoons of water to a pan and bring it to the boil. Reduce the heat and whisk in 25g of the butter until it’s all melted. Keep adding the butter piece by piece until it’s all been added. Bring the melted butter emulsion to 60ºC using a digital thermometer to check progress. When it’s reached the right temperature, add the lobster and poach - keeping the temperature constant - for 6 minutes.While it’s in, check the sauce and adjust the seasoning with salt and the white wine vinegar. Remove the leeks from the frying pan and keep warm. Add a little fresh oil to the pan and put in the crushed potatoes, seasoning them lightly with some salt as you do so.Once the lobster has been poaching for 8 minutes, it’s time to serve. Using a food ring, place a circle of the sautéed leek, and top with the crushed potatoes. Add half of the tail meat, then the rest of the meat, topped by the claw. Spoon the sauce around the plate, with a little drizzled on top of the lobster. Garnish with a little parsley if wished, and serve.Food wasteAs ever, when using double cream, if you have some left and don’t know quite when you’ll use it, you can freeze it for future use. This only really works if it’s double cream. I’m assuming you don’t need ideas from me on what to do with the rest of the bottle of white wine …