Add 1/2 tsp each of salt and pepper to 400g lean ground beef. Form into 12 small balls. Slice 250g of mushrooms. Fry the meatballs in 2 Tbsp hot oill for about 6 minutes then add the mushrooms. Push the meatballs to side of the pan and add 350ml cold water and 100ml heavy cream. Bring to a boil and simmer for about 5 minutes