Cut off the green leaves from leeks; wash and cut leeks slantwise into 1-inch thick slices. Sauté in a little oil and place in a baking pan. Sauté the onion and the ground meat in the remaining oil. Add beef stock, tomato sauce, red pepper, salt and pepper, and bring to a boil. Pour meat mixture over the sautéed leeks. Bake for 1 hour at 375 degrees F. Serve hot.