Heat a large cast iron skillet over medium-high heat.
Cut the steak into 4 portions. Thinly slice each piece against the grain into strips that are 2 inches long.
Add the oil to the skillet. Add the steaks, arranging in an even layer. Cook until browned on the bottom, 2-3 minutes. Turn the steaks, season with salt and pepper. Cook for 1 minute more.
Add the pear and onion. Cook, tossing often, until the pear softens, 1-2 minutes. Add the garlic and ginger, toss until aromatic, about 1 minute. Mix in the broth, gochujang, coconut aminos/tamari, Worcestershire, and brown sugar. Simmer until slightly thickened, 2-3 minutes. Transfer to a bowl. Drizzle with sesame oil. Top with scallions and sliced jalapenos.
Serve the bulgogi with a large platter of butter lettuce leaves. Wrap the meat in the lettuce, then top with the cucumbers. Serve with lime wedges to drizzle the lime juice over the top.