Place beef in a 5- to 6-quart slow cooker. In a skillet, heat oil over medium heat. Add onions, garlic, marjoram, caraway seeds (if using), 1 teaspoon salt, 1/4 teaspoon pepper, and tomato paste; cook, stirring occasionally, for 5 minutes. Stir in flour. Whisk in broth and chili sauce, scraping up brown bits from bottom of pan; bring to a boil. Pour over beef and stir well. Cover and cook on low for about 8 hours or on high for about 4 hours, until beef is tender.