2 tablespoons olive oil
1 cup finely diced onion
1 teaspoon minced garlic
2 pounds lean ground beef
1 cup tomato paste
2 3/4 cups tomato puree
1/2 teaspoon chili powder
1/2 teaspoon Tabasco sauce
1 teaspoon pureed canned chipotle in adobo
1 bay leaf
12 kaiser rolls or hamburger buns
12 slices cheddar cheese (optional)
In a large skillet over medium heat, warm oil, and saute onions until translucent, 5 to 6 minutes.
Add garlic, and saute for 30 seconds. Add ground beef, and saute until well browned, 15 to 20 minutes.
Add tomato paste, tomato puree, chili powder, Tabasco, chipotle and bay leaf. Stir until blended. Raise heat to bring to a boil, then reduce heat to low. Simmer mixture, stirring occasionally, until thick enough to spread on a sandwich, about 45 minutes.
To serve, heat a broiler. Slice the rolls open and place them under the broiler until lightly toasted, turning as necessary. Ladle about 1/2 cup onto the bottom of each roll, and top with cheddar cheese to taste. Return bottom halves to the broiler until cheese just melts. Top with the remaining halves, and serve immediately.