2/3 cup crumbled Stilton (from a 6- to 7-oz wedge, rind discarded)
1/4 cup sour cream
1/4 cup water
2 teaspoons white-wine vinegar
1/4 teaspoon black pepper
2 tablespoons finely chopped fresh chives

Coarsely mash Stilton with a fork in a bowl. Stir in sour cream, water, vinegar, and pepper until combined well, then stir in chives. Season with salt if desired.

Cooks' note:
Dressing keeps, covered and chilled, 3 days.