Cut the pork tenderloin into 1-inch cubes and place them in a medium glass bowl.
In a small jar, whisk together the gochujang, tamari, sesame oil, rice vinegar, grated ginger, and minced garlic until smooth.
Pour the marinade over the pork, tossing to coat thoroughly, and let it sit for at least 15 minutes to absorb the flavors.
Thread the marinated pork onto skewers, alternating with the zucchini slices and red onion wedges.
Season the skewers lightly with sea salt and black pepper.
Preheat a grill pan or outdoor grill to medium-high heat and lightly grease with a touch of oil if needed.
Grill the skewers for 3-4 minutes per side, or until the pork is cooked through and the edges are beautifully charred.
Remove from heat and let rest for 2 minutes before serving.