In a large sauté pan, heat EVOO and begin browning the chicken pieces in small batches making sure not to over crowd the pan. Add the onions, garlic, salt and pepper, and stir to combine. Cook until onions and garlic are soft, about 2-3 minutes. (If your pan is too small to cook all the chicken at once without overcrowding, work in batches, reserving cooked chicken on a plate. Add additional EVOO, if needed, to sauté onions and garlic.)
In a bowl, whisk together the brown sugar, cider vinegar, Worcestershire sauce, hot sauce, tomatoes and chicken stock. Pour into the pot with the chicken. Let this mixture cook for about 15-20 minutes or until reduced.