Optional, heat 2 tablespoons of oil in a large skillet over medium heat. Season stew meat with salt and pepper. Add meat to the skillet, and cook until browned, about 2-3 minutes.
Optional, in the same skillet heat 2 tablespoons of oil over medium heat. Add onions, and brown, about 10 minutes. In the last 1 minute, add garlic.
Place all ingredients in the slow cooker, minus the flour. Cover and cook on high 4-5 hours, or on low for 7-9 hours.
In the last 30 minutes of cooking, take out 1/2 cup of broth. Cool broth, and whisk in flour until smooth. Stir broth/flour mixture back into the slow cooker and cook for 30 minutes.
If the broth/flour mixture is lumpy, blend it until smooth.