Remove bone from chicken legs. Remove outer leaves and trim upper 2/3 of the lemon grass. Cut the trimmed lemon grass into thin slices and finely chop. Combine the boneless chicken and the finely chopped lemon grass with garlic, shallots, ginger, fish sauce, oyster sauce, soy sauce, rice wine, sesame oil, sugar, and black pepper and marinate for at least 2 hours.
Preheat a grill over low heat.
Place marinated chicken on the grill, skin-side down, and cook for 5 minutes over direct low heat. Turn and grill until juice comes out clear when pierced with a fork. Remove, sprinkle sesame seeds on top and serve hot.
To pan fry, heat a nonstick frying pan over high heat until hot. Add a bit of olive oil and place 2 chicken steaks, skin side down, in the pan and let cook until skin is nicely brown. Turn and let cook until juice comes out clear when pierced with a fork. Remove from heat and keep warm. Repeat for the remaining 2 chicken steaks.