Combine oil, ground beef and onion in frying pan. Brown, stirring frequently to break up. Sprinkle with salt, pepper and sage. Stir in flour until well mixed with meat mixture. Add milk all at once. Stir as it boils and thickens. Stir in curry powder. Add more liquid if needed, especially when reheating. Ready to eat or put in casserole. Cover. Bake in 180ºC oven for 20 minutes. Serve with rice or oodles of noodles.