Heat the ghee in a large heavy-bottomed pot over medium-low heat. Add the onions, ginger, and garlic and cook slowly until the onions are very soft, about 15 minutes.
Add the tomato paste, curry powder, cinnamon stick, and red pepper flakes and give it a good stir; season with salt and pepper. Pour in the coconut milk and chicken stock and bring it back to a simmer; cook until the sauce has thickened, about 20 minutes.
Add the tomatoes, chicken, cilantro, and half the lemon juice; continue to simmer until the chicken is cooked through, about 10 to 15 minutes. Taste and adjust the seasoning with lemon juice, salt and pepper.
Serve in bowls over rice and garnish with cilantro and mint leaves.Recipe from Tyler Florence