Add chili powder, minced garlic, onion powder, cumin, salt and seasoning salt, to a bowl; whisk well.
Coat 1/2 of the chili powder mixture onto the rib roast; rubbing vigorously.
Place meat on a baking sheet, cover and refrigerate for up to 4-6 hours.
Add the remaining chili powder mixture, dried onion flakes, brown sugar, tomato, tomato sauce, Worcestershire sauce, soy sauce and water, into a saucepan.
Turn heat on low and cook for 3 to 5 hours, stirring occasionally.
Prepare an outdoor grill for indirect heat and lightly grease.
Place ribs on grill and cover.
Roast 3-5 hours, or until desired doneness.
Brush sauce mixture onto the ribs during the last minutes of cooking.
