Cider: For the wine, substitute 6 tablespoons dry hard cider.

Citrus: Substitute 2 tablespoons lemon, lime, orange, or grapefruit juice for the vinegar and add ½ teaspoon finely grated zest with the shallots.

Herbs: Stir into the finished sauce 1 to 2 tablespoons minced herbs, such as tarragon, fennel fronds, chervil, chives, parsley, or a combination.

For serving with shellfish: you may replace half of the butter with 4 tablespoons Shrimp or Lobster Butter, chilled until solid and cut into 4 pieces (add the plain butter first or the sauce will not thicken).