Line your slow cooker with several layers of folded aluminum foil to prevent the back side from over cooking. (Trust me, this goes a long way at serving time). Spray with non-stick cooking spray.
Heat the cabbage with 1 tbs oil and ½ teas salt in a large bowl in the microwave for 15 to 20 minutes, until softened. Drain the cabbage.
Heat the remaining 2 tbs oil in a large skillet over medium heat. Add the onion, garlic, ginger, and cinnamon, and nutmeg.
Cook. stirring often, until onions are beginning to brown, about 10 minutes.
Place half of the onion mix in a large bowl.
Add the flour to the skillet with the remaining onion mixture and cook for 1 minute.
Stir in the tomato sauce, sugar, and vinegar. Scrap up any browned bits if needed. Season with salt and pepper to taste and let sit for a few minutes on low while you prepare the rest of the recipe.
When cool enough to handle, add bread and milk to the bowl with the onions.
Mash with a fork to form a paste. Mix in the beef, bratwurst, and rice. Season with salt and pepper.
Spread ½ cup of the tomato sauce over the bottom of the foil lined slow cooker. Add ⅓ of the meat mix and top with ⅓ of the cabbage. Repeat 2 more times.
Cover and cook on low for 4 hours.
Remove the foil and allow to cool for 20 minutes before serving.