Preparation Whisk together vinegar, mustard, sugar, 3/4 teaspoon salt, and 1/2 teaspoon pepper in a large bowl. Add oil in a slow stream, whisking until emulsified. Season with salt and pepper. Add lettuce and toss to coat. What to drink: Josmeyer Les Folastries Gewürztraminer '05 Cooks'note:Vinaigrette can be made 1 day ahead and chilled.