450 g / 1 lb French beans
1 large peeled onion
25 g butter
Salt, pepper, white wine vinegar for seasoning
Trim the ends of the beans, and simmer in saucepan of water until tender, about 7 to 10 minutes, then drain. In another saucepan melt the butter. Add the chopped onion, cover and simmer for about 10 to 15 minutes so the onion is soft.
Add the beans to the onion. Toss well so the beans and onion are evenly coated. Reheat for a few minutes, season with the salt pepper and vinegar and serve