Finely chop the basil leaves. Avocado pulp, lemon juice, chopped basil, butter, yogurt and half the zest mix in a blender until it`s creamy. Add salt and pepper to taste and put this cream in the refrigerator for 2 hours.
Finely chop the salmon, mix with soy sauce, finely chopped cilantro, lime juice and a tablespoon of olive oil. Put salmon in empty halves of avocado.
Fill in 1/3. Using a pastry bag, put cream on salmon. Smooth the cream with a spatula. Using a teaspoon, make an indentation in the shape of an avocado seed. Put Sturgeon Lemberg caviar in the recess.