Rub flank steak with ancho chili powder, ground cumin, ground black pepper, garlic powder and Kosher salt.
Let it rest room temp for 5 minutes.
Add corn oil and rub until completely incorporated, cover and refrigerate for 30 minutes.
Bring a large cast iron pan to high heat (about 4 minutes) and sear flank steak on both sides for 2 minutes (each side). Remove from heat and allow to rest for 10 minutes.
Instructions for Taqueria Sauce:
Open 12 oz. can of crushed tomatoes, strain] excess liquid and place tomatoes in a large bowl.
Fold in ground white pepper, white vinegar and Kosher salt.
Mince in 1 clove garlic and juice 2 tablespoons lime juice.
Whisk all together for 1 minutes and refrigerate.
Instructions for Assembling Steak Tacos:
In a large saute pan on medium heat add corn oil. Cook corn tortillas for 1 minute per side.
Remove from pan and cover with a damp paper towel.
Next, bring large saute pan to high heat and sear marinated flank steak for 2 minutes on each side. Shut off heat and set aside. Allow steak to rest 5 minutes.