Heat the oil in a large skillet over medium heat. Add the onion and fry for 6-7 minutes. Increase heat to medium-high; add the ground beef and brown until no longer pink, stirring occasionally.
Drain well and return to the skillet. Add the tomato, jalapeno pepper, garlic powder, cumin, oregano, ketchup, BBQ sauce and Worcestershire sauce. Simmer covered over medium-low heat until mixture begins to thicken, about 30 minutes, stirring occasionally. Taste and adjust seasonings; add salt and pepper if needed.
Meanwhile, toast the English muffins. Serve the Sloppy Joes hot over toasted English muffins; sprinkle with cheese.