Stewed Potatoes and Green Beans with Tomatoes

Cook green beans, potatoes, and garlic in oil with 2 teaspoons salt and 1 teaspoon pepper in a 5-quart heavy pot over medium-high heat, covered, stirring occasionally, until vegetables begin to soften and stick to bottom of pot, about 10 minutes.

Pulse tomatoes with their juice several times in a food processor until coarsely chopped, then add to vegetables. Add water and simmer, partially covered, stirring occasionally, until vegetables are tender, 20 to 25 minutes. Mash a few potatoes into sauce and season with salt and pepper.