Heat oil over medium-high heat in a 5-quart stockpot, and sauté the onions until they begin to turn brown. Add beef and bacon to the pot. Cook, stirring constantly, until beef is browned on all sides. Add tomatoes, potatoes, bell peppers, leek, and garlic. Stir well to combine, then add tomato paste, paprika, caraway seeds, thyme, marjoram, salt, black pepper, and water or stock. Bring the mixture a boil, reduce the heat, and simmer the soup, uncovered, for 1 hour, stirring occasionally. Taste and add more salt if desired.