Dice the pork tenderloin into small half-inch cubes and toss them in a bowl with the chili powder, cumin, sea salt, and black pepper until evenly coated.
Heat the olive oil in a cast-iron skillet over medium-high heat until it begins to shimmer.
Add the seasoned pork to the skillet in a single layer and sear for 3-4 minutes without stirring to develop a golden, crispy exterior.
Stir the pork and cook for an additional 2 minutes until fully cooked through, then drizzle with half of the lime juice to deglaze the pan and coat the meat.
While the pork rests, warm the corn tortillas in a separate dry pan over medium heat for about 30 seconds per side until they are soft and pliable.
Finely shred the red cabbage and mince the red onion and cilantro.
Assemble the tacos by dividing the crispy pork between the two tortillas.
Top with the shredded cabbage, red onion, cilantro, and slices of fresh avocado.
Drizzle the remaining lime juice over the top and serve immediately.