Clean the mushrooms and, depending on their size, possibly halve them. Wash the tomatoes, drain and halve. Peel and finely dice the shallot. Wash basil, dab dry and cut finely except for a few small leaves for sprinkling.
Wash the salad as well, drain well and pluck into bite-sized pieces. Whip vinegar, salt, pepper and 1 tablespoon of oil. Turn tomatoes and lettuce in it. Mix crème-fraîche, milk and basil and season with salt and pepper.
Heat butter in a large pan and fry the mushrooms until golden brown, turning them over. Finally add shallots, fry briefly and season with salt and pepper. Arrange oyster mushrooms and salad on plates.
Spread basil cream-fraîche on top and sprinkle with the remaining olive oil. Serve sprinkled with basil leaves. Baguette tastes good with it.