Preheat your grill to medium-high heat (400-450°F).
Toast the brioche buns cut-side down until golden brown, then remove and set aside.
Lightly coat the Hatch chiles with avocado oil and grill directly over the heat for 2-3 minutes per side until the skins are blistered and charred. Let cool slightly, then remove the stems and seeds before finely dicing.
Make the burger sauce by combining the mayonnaise, ketchup, Worcestershire sauce, Fiesta Rub, and lime juice in a bowl. Refrigerate until ready to build the burgers.
Divide the ground chuck into eight 6-ounce patties. Handle the meat gently and season both sides generously with Fiesta Rub.
Grill the patties for 4-5 minutes per side, cooking until they are just shy of your preferred doneness.
Top each patty with roasted diced green chiles and a slice of white cheddar cheese. Close the lid and cook another 2-3 minutes until the cheese is melted.
Build the burgers by stacking two patties on each toasted brioche bun. Spread on the burger sauce and finish with lettuce, tomato, pickles, and red onion.
Recipe Tips
Chile substitutions: poblano, Anaheim, or jalapeño peppers.
