Finely slice the onion, garlic and celery, then chop the carrot into small pieces.
Heat the oil in a frying pan and gently sauté the chopped vegetables, except the garlic.
When softened, add the herbs and garlic, then tomato purée. Stir for a few seconds to coat, then add the tomatoes, and balsamic vinegar. Season to taste.
Stir for a minute, until the tomatoes slightly caramelise, then add half a glass of water.
Put a lid on and sautée for 5-10 minutes, until you get a thick, silky sauce.
Add the beans, warm through, then serve with fresh herbs scattered on top.