Grosseto-style acquacotta

Slice the onions, peppers, and celery. Heat the oil in a pan, add the onion, and let it brown over very low heat; then, add the sliced peppers and celery. Mix well, add the chopped tomato pulp, and cook over moderate heat for half an hour, stirring occasionally.
Transfer the sautéed mixture into a pot, preferably earthenware, pour 1 liter of water over it, and season with salt and pepper. Bring to a boil and continue cooking for another 5 minutes. Separately, beat the eggs. Arrange 4 slices of bread in each soup bowl, cover them with the beaten eggs, and pour the boiling soup—previously well stirred—over everything. Serve immediately.