Pour oil into a saucepan, add the onions and saute until it gets a glassy / translucent look.
Lower the heat and cook while stirring occasionally until it gets a golden brown look for about 20 minutes.
Pour pureed tomato into a saucepan add salt, black pepper, paprika, garlic, vinegar and the just caramelized onions.
Blend everything together. Olive oil from the caramelized onion turns the reddish sauce to an orange shade. It’s normal.For more detailed instructions check out how to make Low carb sugar free bbq sauce at the Low Carb Condiments.
Cabbage rolls:
Remove the core of the cabbage. It's not absolutely necessary but it will ease our job later on.
Place the cleaned head of cabbage into boiling water until its leaves lose some of the rigidness for about 3 - 5 minutes. To save time start preparing the sauerkraut while the cabbage is boiling on its own.
Take it out from the water and let it cool down. If in hurry dash it into ice cold water. The technique called blanch and shock. Read more about it in the Cooking techniques in our KnowledgeBase.
Dice the onion and garlic.
Mix ground meat with diced onion, salt, paprika, egg, diced garlic and optional black pepper.
When the cabbage cooled to workable temperatures carefully remove the leaves.
Remove the stem if desired.
Fill one leaf at the time with the meat mix according to the leaf size. Generally one leaf can take 2 tablespoons of filling.
Roll it up.
Tuck the ends in.
Pile them up.
Assembly:
Place them into an oven proof dish like a casserole dish.
Pour the tomato sauce over them
Place it into the 390°F/200°C oven until the meat inner temperature reaches 145°F / 60°C for about an hour.