Shrimp Aspic

2 envelopes unflavored gelatin
½ cup cold water
2½ cups tomato juice
1 tablespoon finely grated yellow onion (a Microplane is the tool to use here)
1 teaspoon prepared horseradish
1 teaspoon Worcestershire sauce
½ teaspoon salt
1/8 teaspoon ground hot red pepper (cayenne)
1½ cups finely diced cooked, shelled, and deveined shrimp (about 10 ounces cooked, shelled, and deveined shrimp or 25 to 30 medium-small)
½ cup finely diced green bell pepper
½ cup finely diced celery
6 iceberg lettuce cups

For better flavor, use fresh shrimp, not frozen or canned.

Spritz a decorative, nonreactive 6-cup ring mold with nonstick cooking spray; set aside.
Soften the gelatin in the cold water in a small ramekin. Meanwhile, heat 1½ cups of the tomato juice in a 2-quart ovenproof glass measuring cup by microwaving for 5 minutes at 50 percent power or until steaming.
Scoop the softened gelatin into the hot tomato juice and whisk until dissolved. Mix in the remaining 1 cup tomato juice, the grated onion, horseradish, Worcestershire sauce, salt, and cayenne. Set uncovered in the refrigerator for 1 to 1½ hours or until the consistency of unbeaten egg white.
Fold in the shrimp, bell pepper, and celery and ladle into the mold. Set uncovered in the refrigerator and chill for several hours or overnight until firm.
When ready to serve, divide the lettuce cups among six salad plates. Unmold the aspic by dipping quickly into hot water, then inverting on a large plate. Tip: If the platter is wet, you’ll find the unmolded salad easier to center.
Cut the aspic into six wedges and bed on the lettuce. Pass a small bowl of mayonnaise.