Place the olive oil and butter in a large sauce pan over medium heat. Add the chopped onions, red bell pepper and garlic. Cook for about 3 minutes, stirring often until the vegetables are soft.
Add the chicken legs and season with salt and pepper. Cook for about 1 minute on each side.
Add the chicken broth, orange juice and cook for about 2 minutes scraping the bottom of the pan with a wooden spoon. Add the brown sugar and cover the pot. Reduce the heat to medium and cook for about 45 minutes or until chicken is cooked.
Spoon the sauce over the chicken and serve over white rice. Garnish with fresh cilantro.