Steam the beans in a foil covered colander over your potatoes or blanch in salted boiling water until tender.
Whilst the beans are cooking, make a quick tomato sauce by frying the garlic gently in some olive oil. Add the tomatoes and bring to the boil.
Add a little salt and pepper and simmer for about 15 minutes until you have a thick tomato sauce. Season, to taste.
Stir the beans into the sauce until they are all covered