Whisk together soy sauce, onion, honey, gochujang, ginger, mirin, garlic and black pepper in a large bowl. Add pork and toss to coat; cover and refrigerate at least 4 hours, or up to overnight.
Cook on the Stove Top
Heat a cast-iron skillet over medium-high for 5 minutes. Brush grates of pan with avocado or grapeseed oil. Using tongs, transfer pork slices, letting excess marinade drip off, to skillet in a single layer, making sure not to overcrowd. Cook pork until charred and just cooked through, about 1–1½ minutes per side; transfer to a serving platter.
Repeat cooking process in batches with remaining pork.
Cook on the Grill
Prepare a charcoal or gas grill for high heat. Brush grill grate clean; brush grate with oil to coat. Working in batches if needed, making sure to not over crowd, arrange sliced pork on the grate and grill just until cooked through and browned, about 1½ minutes per side.
Reduce heat to medium. Strain the remaining marinade into now empty skillet and add any juices released from cooked pork. Bring to a simmer, scraping up browned bits from the pan, adn cook until thickened and silky, 3–4 minutes. Off heat, add pork back to the skillet and stir to coat.
Transfer pork back to skillet and top with scallions, serranos, sesame seeds and a drizzle of toasted sesame oil.
Serve with cooked rice, kimchi, and sliced cucumber.
Notes
Cooking the pork can get smoky! Turn the exhaust fan on to avoid smoking out your kitchen.Stove top cooking tips: If the meat is not getting charred on the stove top, increase heat to high. The edges of a cast-iron skillet tend to get the hottest, which is great for charring and caramelizing the meat. Move the meat around as needed to get it charred.*If you use tamari, decrease the amount to 3 tablespoons as it is much saltier than low-sodium soy sauce.**If you don’t have mirin or rice wine, you can use rice vinegar and a bit more honey.To make this spicier: add 1–2 more tablespoons of gochujang or a teaspoon of red pepper flakes.
Nutrition
Serving: 1/6 of the recipeCalories: 196kcalCarbohydrates: 8.5gProtein: 33gFat: 3.5gSaturated Fat: 1.5gCholesterol: 100mgSodium: 703mgFiber: 0.5gSugar: 7.5g