Soak wooden skewers in water for 20 minutes to prevent burning during the searing process.
In a medium mixing bowl, whisk together the gochujang, toasted sesame oil, tamari, raw honey, minced garlic, and grated ginger until smooth.
Cut the pork loin into 1-inch cubes and toss them in the marinade, ensuring every piece is thoroughly coated; let sit for 15 minutes.
Prep the vegetables by cutting the red bell pepper and red onion into 1-inch chunks suitable for skewering.
Thread the marinated pork, bell peppers, and red onion onto the soaked skewers in an alternating pattern.
Preheat a grill pan over medium-high heat and lightly coat with a high-smoke point oil spray.
Grill the skewers for 3-4 minutes per side, turning carefully, until the pork is cooked through and develops a beautiful charred exterior.
Transfer the skewers to a serving plate and garnish with sesame seeds and thinly sliced green onions before serving.