Trim the beans; cut them into 1 1/4 in (3 cm) lengths, rinse and drain.

Heat the oil in a large frying pan or fairly shallow saucepan and fry the onion, garlic and sage gently over a low heat for about 10 minutes, stirring frequently.

When the onion is just tender, add the beans and chopped tomato, a pinch of salt and some freshly ground pepper, stir well and add just enough cold water to cover the beans.

Bring to a very gentle boil, cover and simmer very gently for about 25 minutes or until the beans are tender but still fairly crisp. Tiny, thin French beans will only take about 15 minutes or less. Check whether there is a lot of liquid left in the pan when the beans are nearly done; if there is an appreciable amount, simmer uncovered for the last 5 minutes' cooking time to reduce. Taste and correct the seasoning;

serve very hot. This is a very versatile vegetable dish which can also be served on its own or with crusty bread and goat's cheese as a nourishing light meal.