In a Dutch oven, heat 1 tablespoon oil over medium-high heat. Add onions; sauté until cooked. Add lamb; cook until browned. Add harissa; stir and cook for one minute. Decrease heat to medium; stir in flour. Cook for approximately 1 minute until all flour is absorbed. Slowly pour in heated milk while stir continuously. Reduce heat to medium-low; cook for 15 minutes, stirring occasionally. Thin with additional milk as needed. Season with salt and pepper and stir in cilantro.
Serve over biscuits.