Crab Roulade, Avocado Mousse, Cucumber Sauce and Basil Mayonnaise

1. Preheat a water bath to 85°C.
2. Kill the crabs, then break off the legs and claws. Setting the bodies to one side, fully vacuum the legs and claws in a large pouch.
3. Submerge the bag of legs and claws in the water bath for 10 minutes. Once poached, remove from the pouch and crack each claw with the back of a knife.
4. Flake the white meat from the legs and claws into a bowl and thoroughly go through the meat to remove any pieces of shell. Lightly dress the crab with the olive oil to bind, seasoning to taste.
5. To prepare the roulades, cut the avocados in half and peel off the outer skin. Carefully remove the stone, then cut each half lengthways into 2mm thin slices.
6. Using half an avocado per portion, arrange the slices overlapping on cling film and fill with the dressed crab meat. Roll up the avocado and crab into a roulade shape and chill until ready to serve.
7. For the avocado mousse, blitz the avocados in a blender, adding the crème fraîche to form a smooth purée. Season with the salt and add the lemon juice, Tabasco and Worcestershire sauce to taste, then pass the avocado mixture through a fine sieve. Transfer to a piping bag and reserve until ready to serve.
8. To make the cucumber sauce, juice the cucumbers and weigh out 350g of juice. Combine this with the sugar and vinegar, then whisk through the xanthan gum until fully dissolved. Season to taste, then add the diced melon to the sauce and set aside.
9. Next, prepare the mayonnaise. Whisk the egg yolks, white wine vinegar and mustard together in a bowl until pale.
10. Still whisking, gradually add the oil to the egg mixture until all the oil is emulsified. Blanch the basil leaves quickly in boiling water, transferring to ice water to refresh, then finely chop and stir through the mayonnaise. Season to taste and set aside.
11. To serve, spoon a generous amount of cucumber sauce into the bottom of four deep serving plates, ensuring an even spread of diced melon in each bowl.
12. Pipe a little of the avocado mousse down the centre of each bowl, adding a few dots of the basil mayonnaise, and place one of the avocado and crab roulades on each plate. Season with Espelette pepper and garnish with nasturtium leaves. Serve immediately.

From http://www.greatbritishchefs.com/recipes/brown-crab-roulade-avocado-mousse