Fry a couple of tablespoons of onion (red, spring, white – any sort, even leek) in a mixture of butter and olive oil until soft. Add some garlic, one or two cloves, and some mushrooms if you like. Fry for a further 2-3 minutes. Now throw in a few handfuls of green beans. Stir, then add a glass of white wine and some salt and pepper. Cover with a tight fitting lid and simmer for up to twenty minutes. If the pan is going dry, add a little water. When the green beans are tender, add a tin of flageolet beans. Warm through, then serve garnished with spring onion or parsley.