1. Blanch the potatoes in boiling water for 3-4 minutes then drain thoroughly. Meanwhile heat the oil in a wok or large frying pan and stir-fry the beef for 2-3 minutes or until browned.
  2. Add the mushrooms, pepper, onion, paprika and potato slices and cook for a further minute.
  3. Stir in the tomato sauce and stock, leave to gently simmer for 10 minutes – longer to reduce and thicken the sauce if preferred.
  4. Serve in bowls topped with a spoonful of yoghurt and fresh herbs or a dusting of paprika