In a small bowl add sugar, chili powder, chipotle, cumin, oregano, paprika, salt, pepper, onion powder, garlic, olive oil and lime juice. Mix until combined.
Place steaks in a ziplock freezer bag or dish. Pour marinade over steaks steaks, cover and let marinade 1 hour.
Heat grill on medium high heat. Place steaks on grill over direct heat and cook 3-4 minutes. Flip and cook another 2-3 minutes or until desired doneness. Let rest 10 minutes
While the steaks are resting, warm the corn tortillas on the grill or use a gas flame to char them slightly.
Slice steaks in thin strips, place into warm tortillas and top with your favorite toppings and nacho cheese.
For the nacho cheese sauce
Heat a skillet on medium heat and add heavy cream. Once it begins to bubble on the edges whisk in paprika, chili powder, garlic powder, cayenne and cornstarch. Turn off heat and add cheese whisk until melted.
Notes
You can substitute flank or skirt steak, but it should marinate overnight. And the cooking time with be much faster on the grill. Slice against the grain to ensure that it will be tender.