Soak wooden skewers in water for 20 minutes to prevent burning during the grilling process.
In a small bowl, whisk together the gochujang, tamari, sesame oil, honey, garlic powder, and ginger powder until the marinade is smooth.
Cut the pork loin into 1-inch cubes and toss them in the marinade, ensuring every piece is well-coated, and let sit for 10 minutes.
Cut the red bell pepper into 1-inch squares and the white parts of the green onions into 1-inch lengths, reserving the green tops for garnish.
Thread the marinated pork cubes, bell peppers, and green onion segments onto the prepared skewers.
Preheat a grill or grill pan to medium-high heat and brush the surface with avocado oil.
Grill the skewers for 3-4 minutes per side, or until the pork is cooked through and the edges are beautifully charred.
Garnish the skewers with the thinly sliced green onion tops and toasted sesame seeds before serving.