This vinaigrette, in which the high acidity is balanced by a touch of sweetness, also makes a particularly good marinade for fish or chicken.
Whisk together in a small bowl or shake in a jar with a tight-fitting lid:
      1/4 cup fresh lime juice
      2 tablespoons fish sauce
      1 teaspoon sugar
      Salt to taste
      Ground red pepper to taste
Add in a slow, steady stream, whisking constantly, or add to the jar and shake until smooth:
      6 tablespoons vegetable oil
Taste and adjust the seasonings. Use immediately or cover and refrigerate.