Melt butter in a medium pan over medium heat. Add the onion and cook 5-8 minutes, until it becomes soft. Add the spices. Allow the spices to become fragrant. Add Garlic, ginger, bay leaves. Cook for about 2 minutes.
Place the onion mixture in the slow cooker along with all remaining ingredients.
Cook on low for 6 hours.
Gently stir in the lemon juice and salt.
Serve with lemon wedges, room temp yogurt, extra cilantro and warm bread.