To a large bowl, add chicken legs and quarters, chopped onion, scallions, diced scotch bonnet pepper, and fresh thyme. Season with spice mix, salt and pepper, minced garlic and ginger. Add browning sauce and use hands or a wooden spoon to ensure chicken and seasonings are fully coated in the browning sauce. Cover and marinate in the fridge at least overnight.
Heat canola oil over medium-low heat in a heavy bottom dutch pot. Use a fork to remove onions, scallions, pepper, onion, ginger and thyme from the chicken and set aside. Working in batches, brown chicken in the cast iron pan by searing for 5-6 minutes per side. Chicken should be slightly browned but not fully cooked. Remove browned chicken from pot and set on a paper towel lined plate to catch excess oil.
Remove about 1/2 of the oil from the heavy bottom dutch pot, leaving about 2 tbsp of oil. Add reserved seasonings back to the pot and cook over medium heat for 2 minutes, until garlic and onion become fragrant. Add ketchup, chopped Roma tomatoes and warm water to the pot. Add chicken back to the pot. The liquid should cover about 3/4th of the chicken. Allow the sauce to come to a boil, then cover and reduce to a simmer. Cook for 30 minutes. Uncover and taste the sauce. Adjust seasonings to taste. For a thicker sauce, add breadcrumbs or more ketchup.