Melt butter in a medium pan over medium heat. Add the onion and cook 5-8 minutes, until cooked through.
Add the berbere, cardamom, paprika, ginger and garlic, and cook for 1-2 more minutes, until fragrant.
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, brown sugar, and salt (if needed).
Serve with flatbread and yogurt.
Follow steps 1-2 (above) and place cooled onion mixture into a gallon freezer bag with all remaining ingredients except for the stock.
Remove as much air as possible and freeze for up to 3 months.
Thaw completely, then place in a 5 quart slow cooker with the stock and cook as directed above.
