How to Make It
Light a grill. In a large bowl, stir the vinegar with the 1/4 cup of olive oil, 1 tablespoon of the pink peppercorns and the celery seeds. Add the apples and fennel and toss well; season with salt and pepper. Refrigerate until chilled.
In a small bowl, blend the mayonnaise with the lemon juice, lemon zest and the remaining 1 tablespoon of pink peppercorns; season with salt and pepper. Refrigerate until chilled.
Season the crabs with salt and pepper and brush with oil. Grill over a hot fire, top shell down, until lightly charred and crisp, about 5 minutes. Turn and grill until just cooked through, about 1 minute longer. Spoon the apple-fennel salad onto plates and top each serving with 2 grilled crabs. Serve the lemon mayonnaise on the side.