1 pound ground sirloin or 90 percent lean ground beef
1 cup finely chopped onion
1½ tablespoons mild chile powder
1 tablespoon paprika
1½ teaspoons ground cumin
¾ teaspoon garlic powder
½ teaspoon dried oregano
1½ teaspoons kosher salt
1½ tablespoons tomato paste
1½ teaspoons finely minced chipotle chile in adobo
2 ounces finely shredded cheddar cheese (1/2 cup)
12 (6-inch) corn tortillas
shredded iceberg lettuce
shredded cheddar cheese
Adjust oven rack to middle position and heat oven to 400 degrees.
Combine chile powder, paprika, cumin, garlic powder, oregano and kosher salt in a small bowl.
Heat 1 tablespoon canola oil in a 12-inch skillet over medium heat. Add onion and cook, stirring occasionally until softened, about 5 minutes. Add spice mix to the onions, stirring constantly for 1 minute. Stir in tomato paste and chipotle chile and cook for another minute. Add ground sirloin and cook, using a wooden spoon to break meat into pieces no larger than ¼-inch, until beef is cooked through and no longer pink, 5-7 minutes. Transfer beef to a bowl; stir in cheddar until cheese has melted and mixture is homogenous. Wipe skillet clean with paper towels.
Thoroughly brush both sides of the tortillas with canola oil (or spray lightly with cooking spray). Arrange tortillas, overlapping slightly, on a foil-lined baking sheet (2 rows of 6 tortillas). Bake until tortillas are warm and pliable, about 5 minutes. Reduce oven temperature to 200 degrees.
Place 2 tablespoons of filling on 1 side of each tortilla. Fold and press to close tortilla. The filled tortillas can be covered and refrigerated for up to 8 hours.
Set a small wire rack in a rimmed backing sheet (for first batch of cooked tacos). Heat ¼ cup oil in the skillet over medium to medium-high heat until shimmering. Arrange 6 tacos in the skillet with open sides facing away from you. Cook, adjusting heat so oil actively sizzles and bubbles appear around the edges of the tacos, until tacos are crispy and deeply browned on 1 side, about 2-3 minutes. Using a spatula, carefully flip tacos. Cook until browned on second side, about 2 minutes, adjusting heat as necessary.
Remove skillet from heat and transfer tacos to a paper towel lined plate and blot tops with paper towels. Transfer tacos to prepared rack and place in oven to keep warm. Return skillet to medium to medium-high heat and cook remaining tacos.
Serve tacos with your favorite garnishes, rice and beans.