Here, freshly shucked oysters shimmer with mignonette gelee, the traditional vinegar sauce prepared with a little gelatin.
Mix shallot, pepper, and vinegars in a small bowl. Sprinkle gelatin over 1 tablespoon water in another bowl, and let soften, about 5 minutes.
Heat remaining 3 tablespoons water in a small saucepan until steaming. Stir in gelatin mixture. Pour some of the hot liquid into the bowl that the gelatin was in, swirl around, and pour back into pan. Cook over medium heat, stirring, until gelatin dissolves. Pour through a sieve into vinegar mixture. Refrigerate until set, at least 3 hours (or overnight).
To serve, spoon about 1/2 teaspoon gelee onto each oyster (amount may differ depending on the size of each oyster), and serve with horseradish and lemon wedges.