Combine onions, garlic, ghee, ginger, chili powder, coriander, turmeric, cinnamon, cumin, salt, pepper, and tomatoes in the slow cooker and mix well.
2 onions, 3 garlic cloves, 3 tbsp. ghee, 2 tbsp. fresh ginger, ¼ tsp. ground coriander, ¼ tsp. turmeric, ½ tsp. cinnamon, ½ tsp. ground cumin, 1 28 oz. can diced tomatoes, Sea salt and ground black pepper to taste, 2 tsp. chili powder