In a large pot, sauté the thinly-sliced onions in some oil. Gradually add all of the other vegetables, chopped into large pieces. Let them slowly soften for about 10 minutes. Then add enough water to almost fill the pan and add the beans. Add salt and pepper and cook over low heat for about two hours. Let it stand. Serve in earthenware bowls with a little genuine Tuscan extra virgin olive oil with a full, fruity flavor. You may wish to add a bouillon cube.