In a pot, melt the ghee, then add the onion, stirring until it turns yellow, and then add the garlic. Add the tomato, stirring then add lemon, spices, salt, chili pepper and tahini. Stir the ingredients for 2 minutes. Add the pureed beans then stir it with the rest of the ingredients for a few minutes. Afterwards, put it in a serving dish. Stir in the olive oil to taste.