Clean the beans, wash them and cut them diagonally into slices. Cook in boiling salted water for about 10 minutes. Pour off, rinse with cold water and drain. Peel the vegetable onion and cut into rings.
Wash the mushrooms, drain, clean and cut in half. Cut the bacon into pieces, leave it crispy in a coated pan, take it out and let it drain on kitchen paper. Fry the mushrooms and onions in the frying fat for 2-3 minutes.
Let it cool down. Whisk vinegar, salt, pepper, sugar and mustard in a bowl. Finally, stir in the oil. Mix beans with mushrooms, onions and vinaigrette. Season to taste with salt and pepper.
Wash the thyme, dab dry and remove the leaves. Sprinkle bacon and thyme over the salad. Serve with farmhouse bread.