Don't miss out on our special Christmas issue with free 2023 calendar - subscribe by 11 October!
Peel the prawns. Rinse them in a large sieve under a cold tap, then pat dry with kitchen paper. Lay the prawns in a shallow dish and squeeze over 1 tbsp of the lime juice, then add a twist of pepper. Set aside.
Chop the cucumber into small dice and tip into a dish. Spoon over the vinegar, scatter over the dill and a grating of pepper, then set aside. Halve, stone and peel the avocado, then chop into small dice. Spoon over the rest of the lime juice and toss together gently with a twist of pepper.
For the sauce, mix together the mayonnaise, fromage frais and ketchup. Stir in the Tabasco, Worcestershire and brandy with a twist of pepper.
To serve, put a small spoonful of the sauce into the bottom of each cocktail glass. Very coarsely chop most of the watercress, leaving a few sprigs whole. Lay the chopped watercress on top of the sauce. Drain the cucumber well, then spoon it over the watercress with the avocado. Pile over the prawns, then spoon over the rest of the sauce. Tuck in the sprigs of watercress and serve with a sprinkling of cayenne.