Make a cross with sharp knife at the base of each tomato, just to split the skin. Plunge into boiling water for 1 minute, or until the cross at the base starts to open up.

Remove with slotted spoon and peel off the skin, which should come away easily. Remove the core and seeds, and then roughly cut the flesh.

Heat oil in large saucepan and sauté the onions until soft. Add the ham or bacon, salt and pepper. Add the chopped tomatoes and the pesto and the water.

Leave to cook for about 1 hour, simmering gently with lid on. Stir from time to time.

Toast the bread in the oven and use to line the bottom of a large serving bowl.

Pour the soup into the bowl, sprinkle with the Parmesan cheese, season with more salt and pepper and drizzle with olive oil.

Leave for 5 minutes before serving or it can be served cold.