Fire marinade: add all ingredients from the fire marinade to a medium-sized bowl and stir to combine very well. This marinade can be stored in the refrigerator in a sealed container for up to a week. This marinade should be enough for 6 cheesesteaks.
Steak cooking: add 1/3 pound of thinly sliced steak to a small bowl. Stir 2 tablespoons of fire marinade into the meat. Mix well to incorporate the marinade all over the steak.
Place a griddle or large skillet over medium-high heat. Add a little oil to the griddle or skillet, and when it starts to shimmer, place the marinated steak on the hot surface.
Cook the steak for around 6 minutes or so. Try to use your spatula to break the meat up a little while it is cooking.
While the steak is cooking, slice your sandwich roll and add it to the griddle or pan to warm up. Don't let it turn brown, but warming it up a little will soften the roll.
When there's no more visible pink color to the steak, it should be almost done cooking. Top the steak with your slices of mozzarella. Stir the meat in with the cheese a little bit to help the mozzarella soften and melt.
Sandwich assembly: add a couple of tablespoons of kimchi to the inside of your roll.
Top the kimchi with your cooked steak and cheese mixture to complete the sandwich. Add any additional cheese sauce if needed.
Serve and enjoy.
Notes:
Optional cheese sauce ingredients: sodium citrate is not going to be something you can find at the grocery store. Here is the brand of Sodium Citrate that I use from Amazon.
Optional cheese sauce instructions: right after you add the meat to the skillet or griddle, you can start this sauce.
Add water and sodium citrate to a medium-sized pot over medium heat and bring to a simmer. Slowly add the cheese in batches until it's all melted, stopping to stir occasionally. Keep the sauce barely simmering until it's time to build the cheesesteak.
If the sauce is too thick, you can add a little bit more water to get it to a thinner consistency. The sauce can be reheated in a pot or in the microwave.