For the Kimchi: Place the Napa Cabbage (1 pound) in a large bowl. Add Water (10 cup) and Kosher Salt (1/4 cup) and stir to combine. Let sit for 10 minutes.
Slice the Sirloin Steak (1 pound) across the grain on a diagonal bias. Lightly pound each slice of beef to tenderize.
Combine Crushed Red Pepper Flakes (1/8 cup), Granulated Sugar (1 tablespoon), Fish Sauce (1/4 cup), Garlic (1/2 bulb), Fresh Ginger (1 tablespoon), Scallion (3), Carrot (2) a smaller bowl to make a paste.
Rinse the salted cabbage and pat dry.
Add the paste to the sliced cabbage and mix well with your hands.
Store the mixture in an airtight jar or plastic container. Press the contents down to protect the kimchi from being exposed to too much air. You may use the kimchi right away, or keep it at room temperature to ferment for a few of days – the flavor will intensify if allowed to ferment.
In a large bowl, combine the Garlic (2 clove), Yellow Onion (1/2), Pear (1/2), Soy Sauce (2 tablespoon), Sesame Oil (2 tablespoon), Brown Sugar (2 tablespoon), and Gochujang (1 tablespoon).
Add the meat to the the marinade and mix well, making sure that each piece is throughly coated. Cover and refrigerate for at least 1 hour and up to 8.
Warm the Vegetable Oil (2 tablespoon) in a large skillet over medium-high heat. In a single layer, add the beef drained from the marinade (work in batches if needed). Cook for 1 minute (do not move the beef). Sprinkle with a pinch of salt, then begin to stir and toss the beef for 1-2 minutes, until just cooked. Remove from heat and set aside.
Warm the Tortilla (24) in a grill pan or other heavy-bottomed skillet. Heat the pan to medium-high heat and warm each tortilla 1 to 2 minutes per side – you want to heat the tortillas just enough to slightly char and add a bit of crispness, but not so much that when you fold it, it cracks.
Wrap the tortillas in a clean tea towel to keep warm and set aside.
Using two tortillas per taco, add the bulgogi, kimchi, Sour Cream (8 ounce), Sriracha (to taste), Sesame Seeds (4 tablespoon), Fresh Cilantro (4 tablespoon), and a little Lime (2) juice. Serve warm.