Place habanero pepper on a baking sheet and roast for 10 - 15 minutes or until soft.
Combine roasted habanero pepper, olive oil, vinegar, garlic, salt, cilantro and lime juice in a food processor. Process until well blended.
Place chicken in a bowl. Pour marinade over the top. Cover and refrigerate for at least 2 hours.
When ready to cook. Preheat oven to 400 degrees.
Place chicken in a baking dish or oven proof pan. Pour marinade over the top. Lay sliced onions around chicken. Cook in preheated oven for 35 - 40 minutes or until chicken is cooked through and browned.
Transfer chicken to a serving platter and spoon sauce over the top. Serve.