How to Make a delicious vegetarian cassoulet stew

A perfect vegetarian version of a delicious stew! For this recipe, you will need: 1 large chopped onion, 1 large chopped leek, 3 chopped carrots, 1/4 cup olive oil, 4 minced garlic cloves, 14 ounces diced tomatoes, 4 tablespoons tomato paste, 3/4 pound white beans, 1 tablespoon sherry vinegar + 1/2 cup water (or 1 cup dry white wine), thyme, vegetable stock, 1 cup breadcrumbs and 1 sliced baguette.