Pack a large serving platter or shallow bowl with crushed ice in an even layer about 1 to 1.5 inches deep. Keep chilled while you shuck oysters so they remain cold.

Shuck oysters

Rinse shells under cold running water to remove grit. Using an oyster knife and a thick glove or towel to protect your hand, insert the tip at the hinge and twist to pop the shell. Run the knife along the top shell to sever the muscle and discard the top shell. Slide the knife under the oyster meat to free it from the bottom shell while keeping the oyster level to retain its liquor. Arrange each shucked oyster, cup-side down, on the bed of crushed ice. Repeat until all 12 oysters are shucked. Keep refrigerated if not serving immediately.

Champagne Mignonette

Mince shallot

Finely mince the shallot so it measures about 1/2 cup. A fine dice gives the best texture for the mignonette.

In a small bowl combine the minced shallot, champagne vinegar, dry sparkling wine (or additional champagne vinegar), granulated sugar, coarse sea salt, and freshly ground black pepper. Stir until the sugar and salt dissolve. Taste and adjust balance — add up to 1/2 teaspoon more sugar if too acidic, or a pinch more salt if needed. Let the mignonette sit at least 10 minutes at room temperature (or up to 1 hour refrigerated) to allow the flavors to meld. Bring to near room temperature before serving so it isn’t too cold on the oysters.

Accompaniments

Prepare lemons

Cut the lemon into 6–8 wedges for squeezing. Arrange wedges in a small pile on the serving platter or a separate small dish.

Toast brown bread and butter

Lightly toast the brown bread slices until golden and slightly crisp. While still warm, spread each slice with softened unsalted butter. Cut slices into halves or serve whole alongside the oysters. For a restaurant touch, rub the warm toast lightly with a cut clove of garlic before buttering (optional).

To serve, place the chilled platter of oysters at the center with the mignonette in a small ramekin or pour spout, lemon wedges, and buttered brown bread on the side. Provide small forks or oyster forks and napkins. Guests should spoon a small amount of mignonette or squeeze a little lemon over each oyster and eat directly from the shell.