I combine oregano, garlic powder, onion powder, cumin, and chipotle (or chili powder) in a small bowl. Then I rub this mixture all over the chicken tenderloins so they’re well coated. I leave them aside while the sauce and chorizo cook so the spice flavors settle into the meat.
While the chicken rests, I warm a small saucepan over medium heat. I pour in milk and add diced or chopped white American cheese, stirring occasionally until the cheese melts completely and becomes smooth. Once smooth, I reduce heat to keep it warm without boiling.
I heat my skillet (cast-iron if possible) over medium-high heat. I add the raw Mexican chorizo, break it up with a spatula, and cook for about 5 minutes until done. Then I remove the chorizo with a slotted spoon, leaving the grease behind.
Next I deglaze the pan with lime juice, scraping up browned bits, then add the chicken in a single layer and cook 2-3 minutes per side until browned and cooked through (internal temp ~165°F).
After the chicken is cooked, I place it back under the cooked chorizo, pour the cheese sauce over both. If using, I warm tortillas and either serve everything over rice or let people make their own tacos. Serve immediately so the cheese is melty and the texture is perfect.