Heat the avocado oil in a 12-inch cast iron skillet over medium-high heat. Once the oil shimmers (about 1 minute), swirl to coat the bottom, then reduce heat to medium. Add the potato cubes in a single layer and cook for 6 minutes, stirring every minute. The potatoes should develop golden brown edges and slight softening but still be firm when pierced.

Push the potatoes to one side of the skillet. Add the ground beef to the empty side, breaking it up with a wooden spoon. Add the diced onion and red bell pepper directly onto the beef. Season with salt and pepper. Cook for 5 to 6 minutes, breaking the beef into small crumbles as it browns until it loses all pink color. If beef releases excess fat, carefully spoon out excess grease, leaving about 1 tablespoon.

Add the green chiles, chili powder, cumin, smoked paprika, and cilantro to the skillet. Stir everything together, ensuring the spices coat the beef and potatoes well. Continue cooking for 6 to 8 minutes, stirring occasionally, until the potatoes are easily pierced with a fork and the beef is fully cooked through. Taste and adjust seasoning as needed.

Sprinkle the shredded cheese evenly over the top of the skillet. Let it sit for 1 minute without stirring, allowing the cheese to melt completely. Remove from heat, garnish with extra cilantro if desired, and serve immediately.