A basic mignonette is like a vinaigrette without the oil, giving cold, salty oysters a bit of extra brightness with a splash of tart vinegar and mild, oniony shallots. This version adds the juice of sweet and just-barely-bitter grapefruit to mellow the vinegar and highlight the floral spiciness of black pepper.

Makes about two cups, probably way too much, unless you're really going to town with the oysters. Halve or quarter the recipe as need.

• Juice from 1 Ruby Red grapefruit
• Equal amount of good red wine vinegar
• 2 teaspoons minced shallot
• 1 teaspoon cracked black pepper

1. Mix together all ingredients. Let sit at least 10 minutes before serving.