Ingredients

3 tablespoons olive oil

1 tablespoon white-wine vinegar

1 teaspoon Dijon mustard

1/2 cup lightly packed fresh basil leaves

Coarse salt and ground pepper

6 large plum tomatoes, or medium vine-ripened tomatoes

Preparation

In a blender or mini food processor, combine oil, vinegar, mustard, basil, and 1 tablespoon water; blend until smooth. Season with salt and pepper. If not using right away, transfer to an airtight container; refrigerate, up to overnight.

Slice tomatoes, and arrange on a serving plate; drizzle with dressing. Serve immediately.