Crayfish Salad with French Cocktail Sauce

Name: Crayfish Salad with French Cocktail Sauce
Ingredients: 1 pink grapefruit; 2 ripe avocados; 1/2 lemon; 1 head Boston lettuce, washed, dried, and cut into thin strips; 4 plum tomatoes, peeled, seeded, and finely chopped; 12 leaves tarragon, finely sliced; The reserved grapefruit rind (see method); 1/2 bunch tarragon, leaves and stems; 1/4 cup salt; 1 teaspoon cracked peppercorns; Pinch of cayenne pepper; 3 pounds crayfish, preferably live, rinsed under cold running water, or 1 pound peeled cooked crayfish; The reserved grapefruit juice (see method); 1 large egg yolk; 1 tablespoon Dijon mustard; Salt and freshly ground white pepper; Small pinch of cayenne pepper; 1/4 cup vegetable oil, preferably grapeseed or safflower oil; 2 1/2 tablespoons ketchup; 1 teaspoon white wine vinegar; 1 teaspoon Worcestershire sauce; 1/2 teaspoon Cognac or Armagnac; 2 tablespoons sliced blanched almonds, toasted, for serving