Cut the meat into bite-sized cubes, clean and halve the mushrooms, peel and halve the shallots. Heat the oil in a pan or wok, fry the meat all over, then remove it and keep warm.
Heat the butter in a pan or wok, steam the mushrooms and shallots in it for approx. 5 minutes. Pour in white wine and reduce to half over high heat. Reduce the heat, add the meat and stir in the creme fraiche. Then simmer for 10-15 minutes. Season with salt and pepper. Sprinkle the ragout with chervil and serve.