Marinate the steak: In a bowl, mix together soy sauce, lime juice, garlic, cumin, chili powder, and black pepper. Place the steak in a ziplock bag or shallow dish and pour the marinade over it. Let it marinate for at least 15 minutes (or overnight in the refrigerator for deeper flavor).
Cook the steak: Heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Remove the steak from the marinade and pat dry with paper towels. Cook the steak for about 4-5 minutes per side for medium-rare (adjust time based on thickness and desired doneness). Remove from heat and let rest for 5 minutes before slicing thinly against the grain.
Prepare the eggs: In another skillet, heat butter over medium heat. Crack eggs into a bowl, whisk until combined, and season with salt and pepper. Pour into the skillet and cook, stirring occasionally, until soft scrambled, about 2-3 minutes.
Warm the tortillas: Heat the remaining tablespoon of olive oil in a clean skillet over medium heat. Warm each tortilla for about 30 seconds per side until pliable and slightly crispy at the edges.
Assemble the tacos: Place a warm tortilla on a plate. Add a portion of sliced steak, scrambled eggs, shredded cheese, avocado slices, diced red onion, jalapeño (if using), and cilantro. Serve with lime wedges for squeezing over the top.