Decadent Steak Fajitas

Instructions

1. Marinate the steak. In a bowl or zip-top bag, mix oil, lime juice, soy sauce, garlic, brown sugar, chili powder, cumin, smoked paprika, salt, pepper, and cayenne (if using). Add steak and coat well. Marinate at least 30 minutes and up to 8 hours in the refrigerator. Before cooking, let the steak sit at room temp 20 to 30 minutes so it is not ice-cold.
2. Heat the pan until it is truly hot. Place a large cast iron skillet over high heat and let it heat until very hot and just starting to smoke, usually 3 to 5 minutes depending on your stove. You want real heat here for a proper sear.
3. Sear the steak. Remove steak from marinade and let excess drip off, then pat lightly dry for better browning. Add 1 tablespoon oil to the hot pan, then lay in the steak. Sear 3 to 5 minutes per side, depending on thickness, until deeply browned and the steak releases easily when you try to flip it. Check the thickest part. These are pull temperatures: pull at 125 to 130°F for medium-rare, 135°F for medium, or cook to your preference.
4. Rest, then slice. Transfer steak to a cutting board and rest 5 to 10 minutes. Slice thinly against the grain. This is non-negotiable if you want tender fajitas. If you are working with flank steak, slice it into a few shorter sections first, then slice each section against the grain.
5. Char the peppers and onions. While the steak rests, add onion and bell peppers to the same skillet (add a splash more oil if the pan is dry). Cook over high heat 6 to 8 minutes, stirring only occasionally, until softened with charred edges. Do not overcrowd the pan. If your skillet is smaller, cook the veggies in batches so they char instead of steam. Add jalapeño if using and cook 1 minute more. Season with a pinch of salt, to taste.
6. Finish with a quick lime-butter glaze. Lower heat to medium. Push the veggies to one side of the pan (or clear a little space in the center), then add the butter. Once melted, add 2 tablespoons lime juice and 2 to 3 tablespoons water to loosen everything up. Stir and toss until the veggies look glossy and the liquid lightly coats them, 30 seconds to 1 minute. It is not a thick sauce, it is a shiny, tangy finish. Return sliced steak and any juices to the pan and toss to coat. Turn off heat. Stir in cilantro if using.
7. Warm tortillas and serve. Warm tortillas in a dry skillet or directly over a low flame. For corn tortillas, warm briefly in a dry skillet until pliable, then stack in a towel to keep them soft so they do not crack. Pile steak and veggies into tortillas, then top with crema, cheese, salsa, and a squeeze of lime.