In shallow baking dish or bowl, combine chicken with garlic and rum and let marinate, covered, in the refrigerator for a few hours or overnight.

In a medium-sized casserole or heavy pot, heat the oil over medium-high heat. Add the onions and lemongrass and saute until tender and fragrant, about 3 minutes, stirring occasionally. Add the chicken and saute until cooked through, about 4 to 5 minutes. Add coconut milk, curry powder, and sesame oil and heat through. Add hot pepper, if using. Serve with rice and garnish with freshly chopped cilantro.