Step 3) Start by scattering some of the onion, jalapeños, and cilantro on the bottom, pour over some of the marinade, then place 2–3 pieces of steak, pushing it down into the marinade and flipping over to make sure both sides are covered. On top of this first layer of meat, once again add more of the onion, jalapeño and cilantro mixture and more marinade, followed by more steak. Repeat this layering process until you have used up all of the steak pieces. Any leftover marinade, onions, jalapeños, and cilantro, scatter over the top of the baking dish with the meat. Cover well and let this marinate in the refrigerator for at least 4–6 hours, or up to 24 hours.