Cut the pork loin into 1-inch cubes and set aside in a medium bowl.
In a small jar, whisk together the gochujang, coconut aminos, toasted sesame oil, grated ginger, and minced garlic until smooth.
Pour the marinade over the pork cubes and toss to ensure every piece is well-coated, then marinate for 20 minutes.
Prepare the vegetables by cutting the red bell pepper and red onion into 1-inch chunks.
Thread the marinated pork, bell pepper, and onion onto skewers in an alternating pattern until all ingredients are used.
Season the assembled skewers evenly with sea salt and black pepper.
Heat a grill pan or outdoor grill to medium-high heat and lightly grease with a high-heat cooking spray.
Grill the skewers for 10 to 12 minutes, turning every few minutes, until the pork is cooked through and the edges are beautifully charred.