1 head butter lettuce

1/4 cup white-wine vinegar

2 tablespoons finely chopped shallot

1/2 teaspoon salt

1/2 teaspoon Dijon mustard

1/4 teaspoon black pepper

3/4 cup olive oil

Whisk together vinegar, shallot, salt, mustard, and pepper until salt is dissolved. Add oil in a slow stream, whisking until emulsified. Wash and thoroughly dry lettuce. Tear into bite-sized pieces. Toss with dressing.