Pat the steak dry with paper towels and trim off any large pieces of fat. Cut meat against the grain into ¼-inch thick slices and add to the bag of seasoning. Add olive oil and lime juice and seal bag, squeezing out as much air as you can. Transfer to refrigerator for at least 30 minutes, or up to 4 hours.

Heat a large cast iron skillet over medium-high heat. Once hot (this takes a few minutes), add peanut oil and turn to coat bottom of the skillet. Add onions and break them up w a wooden spoon. Lower heat to medium-low and season with ½ teaspoon salt. Constantly stir until it stops sizzling.

When the pan cools down, add butter. Stir every 10 min or so until caramelized, about 45 minutes to 1 hour. Transfer to a bowl, scraping out all the browned bits and cover. DO NOT CLEAN THE PAN.

Return skillet to medium-high heat. Pan should be smoking.

Drain the marinade from the bag of steak and put the meat in the hot skillet. Spread over the bottom of the pan using metal tongs, turning until browned on all sides, about 2-3 minutes. Once browned, place into the bowl with onions and cover.

Add peppers to pan and season with ½ teaspoon salt. Cook, stirring constantly. When they start to stick to the bottom of the pan, lower the heat to medium.

Add onions and meat back into the skillet, then add tomato paste, turn off heat and stir in until well combined. At this point, you can pour in soy sauce to get that sizzling sound and smoke for when you bring it to the table.

Serve fajitas with warmed flour tortillas, Greek yogurt, and lime wedges alongside.