Wash the turkey breast, dab dry and cut into 3 cm cubes. Heat 2 tablespoons of oil in a large frying pan. Sauté the meat in it for about 5 minutes, possibly in two portions while turning. Remove the meat and deglaze the frying pan with stock, cream and white wine to create a slightly brownish sauce. Season with salt and pepper and bring to the boil. Stir starch with 2 tbsp. water until smooth, thicken sauce with it, bring to the boil again. Put the meat back into the sauce
Clean the mushrooms, wash them and cut them into thick slices. Wash the tomatoes, dab dry and cut in half crosswise. Clean and wash spring onions, dab dry and cut into rings. Pour boiling water over the peas and drain after about 3 minutes. In a second frying pan heat 1 1/2 tbsp. oil and fry the mushroom halves until golden brown, season with salt and pepper, remove and add to the meat. Do the same with the remaining mushrooms. Heat 2 tablespoons of oil in a frying pan, fry the tomatoes briefly on the cut side, add the spring onions and fry briefly more until the onions are soft.
Add the tomatoes, spring onions and peas to the turkey ragout and reheat. Season to taste again. Wash the chervil, dab dry and chop. Sprinkle turkey ragout with chervil. Serve with potato rösti