Preheat oven to 375F.

Heat a medium Enameled Cast Iron Skillet or Carbon Steel Frying Pan over medium. Add chorizo and cook, breaking it into clumps and stirring occasionally, until cooked through and slightly browned, about 5 minutes. Transfer to a paper towel-lined plate and wipe out Skillet.

Return Skillet to medium heat and add oil. Add onion and salt and cook, stirring, until softened and just starting to brown, about 4 minutes. Add garlic and cook 1 minute more. Stir in green chiles and scrape bottom of pan to loosen any browned bits.

Gently fold half of cheese into onion-chile mixture. Top with remaining cheese and transfer to oven to bake (watching carefully!) until cheese is just melted and bubbling around edges, about 8 minutes. Do not overcook or cheese will become rubbery.

Remove from oven and top with chorizo. Top with cilantro and pickled red onions or jalapeños, if desired. Serve in skillet with chips and/or tortillas and pico de gallo (if using) alongside.

If necessary, reheat queso, watching carefully, until warmed through (reheating too many times will result in tough texture).