Jalapeños or not, these sliders are on fire!
Season steak; coat with 2 tsp. oil. Cook on griddle over high, turning once, 5 minutes. Let rest 5 minutes; thinly slice. On griddle, cook onion and chorizo in remaining 3 tsp. oil over high until soft, 2 minutes. Stir in steak; divide among rolls. Top with avocado and jalapeño, if using.
Hot or Not: Give your guests options: Put jalapeños on only some of the sliders. Skewer a chile on top to let folks know where the heat’s at.