Clean, peel and slice the carrots. Wash and clean the mushrooms and mangetouts. Cut mushrooms into slices, halve sugar snap peas crosswise. Dice turkey breast and fry in portions in hot oil for 5 minutes each.
Remove and season with salt and pepper. Fry the mushrooms briefly in the frying fat. Bring the stock to the boil. Steam carrots for about 2 minutes. Add sugar snap peas and cook for another 2 minutes. Mix meat, vegetables, stock, mustard and cream and bring to the boil.
Add sauce thickener and bring to the boil again. Season with salt and pepper and garnish with chervil.