Mix together the ground beef, bread crumbs, 2 onions, curry powder, Italian seasoning, egg, garlic, salt and pepper. Gradually mix in the milk; you might not need all of it--just enough for a good meatball-making texture. Make meatballs that are about 1.5 inches in diameter. In a greased baking dish, bake them for 30 minutes at 375.
Make the sauce while the meatballs are baking. Melt the margarine in a saucepan over medium heat. Add the remaining onions, and cook until browned. Stir in the ketchup, beef stock, steak sauce, Worcestershire sauce, vinegar, instant coffee, brown sugar and lemon juice. Bring to a boil over medium heat, and simmer, stirring occasionally, until the meatballs are done.
Remove the meatballs from the oven, and drain any excess grease. Pour the sauce over them, and return to the oven. Bake for an additional 30 minutes.
The original author says that they taste better if they've been made a little in advance, allowed to cool, and then reheated at 200 degrees for about 15 minutes.