Chipotle Burgers w/Roasted Garlic Ketchup

2 pounds ground sirloin
1 medium onion, peeled and cut in 1/2
2 tablespoons Worcestershire sauce, eyeball it
2 chipotles in adobo and 2 tablespoons of adobo sauce
2 tablespoons grill seasoning, a couple of palm fulls, (recommended: Montreal Steak Seasoning by McCormick)
1 tablespoon extra-virgin olive oil, plus some for drizzling
3 cloves garlic, finely chopped
3 tablespoons brown sugar
1/4 cup vinegar
1 (15-ounce) can crushed fire roasted tomatoes, about 2 cups
Salt and pepper
12 slices, 1/2-inch thick, brick-cut smoked Cheddar or sharp Cheddar, (recommended: Cabot), optional
12 small round rolls, split
(Many markets sell mini Keiser rolls or use dinner rolls in any flavor you like)

Preheat grill pan to high.

Place the meat in a bowl. Cut the onion in half. Grate half the onion into the meat using the small grate on a box grater. Chop and reserve the other half onion. Add Worcestershire, chipotles and sauce and grill seasoning to burgers. Drizzle a little extra-virgin olive oil over the bowl and mix meat. Score the meat into 4 sections. Make 3 mini-burgers, each 3 inches wide, 1-inch thick, from each half-pound of meat.

Heat a small sauce pot over medium heat. Add extra-virgin olive oil and garlic. Cook garlic 2 to 3 minutes then add sugar and vinegar, cook 2 minutes more and stir in tomatoes. Season sauce with salt and pepper and allow it to reduce 5 to 6 minutes more.

Grill meat 2 to 3 minutes on each side and top with cheese, if you like.

Place burgers on buns and top with raw chopped onions and warm fire roasted ketchup and serve.