If you can't find heirloom tomatoes near you, this salad would also be delicious with any ripe tomato from garden or market.

Ingredients

　　1 1/2 tablespoons red-wine vinegar

　　3/4 teaspoon salt

　　1/2 teaspoon Dijon mustard

　　1/4 teaspoon black pepper

　　1/4 cup olive or vegetable oil

　　3 pounds mixed heirloom tomatoes, halved if small or cut into 1/2-inch wedges if medium or large

　　Whisk together vinegar, salt, mustard, and pepper in a large bowl. Add oil in a slow stream, whisking constantly until dressing is emulsified. Add tomatoes and gently toss to coat. Season with salt and pepper.