Creamy Trout Mousse

2 trouts (6 oz ea. cleaned) * 1 whole egg 1 egg white 1/4 pint olive or sunflower oil 5 tablespoon creamy yoghurt 1 teaspoon dijon mustard 1 1/4 teaspoon gelatine powder (or more) 1 fresh parsley & tarragon 1/2 cucumber 1 caster sugar 1 tarragon vinegar *Note: In lieu of fresh trout, 1/2 lb…