Oysters with Mignonette Granita

Combine the sherry vinegar, very finely minced shallots, cracked black pepper, and cold water in a small bowl. Stir to combine. Taste: it should be sharply acidic with a pungent shallot note and a flicker of pepper heat. Adjust the balance with a touch more water if very sharp, or an extra pinch of cracked pepper for more heat. The shallots will soften slightly in the vinegar over time.

Pour the mignonette liquid into a wide, shallow freezer-safe dish — the thinner the layer, the faster and more evenly it freezes. Place in the freezer. After 45 minutes, drag a fork across the partially frozen surface to break it into crystals. Repeat every 30 minutes for 2 hours total, until you have a loose, shimmering mass of sharp vinegar-shallot ice crystals.

Hold each oyster in a folded kitchen towel, flat shell up, hinge toward you. Insert an oyster knife into the hinge at a 45-degree angle. Apply firm, twisting pressure until the hinge pops. Slide the knife along the inner surface of the flat top shell, severing the adductor muscle. Discard the flat top shell. Sever the muscle on the bottom cup shell as well. Check the liquor: it should be clear and faintly salty — milky or muddy liquor means the oyster is stressed. Arrange on the crushed ice immediately.

Arrange the shucked oysters in their cups on a large platter of crushed ice — the ice keeps them cold and holds them level. Place a half-teaspoon of mignonette granita on top of each oyster just before serving. Add a tiny pinch of flaky salt if the oysters are very mild. Serve immediately, before the granita melts completely.