Soak wooden skewers in water for at least 20 minutes to prevent burning during the grilling process.
In a medium bowl, whisk together the gochujang, tamari, raw honey, grated ginger, minced garlic, rice vinegar, and red pepper flakes.
Cut the pork tenderloin and pork belly into uniform 1-inch cubes to ensure even cooking across all pieces.
Add the pork cubes to the marinade and toss until every piece is thoroughly and thickly coated in the sauce.
Thread the pork onto the skewers, alternating between the lean tenderloin and the rich pork belly pieces for balanced flavor.
Preheat a grill or grill pan to medium-high heat and lightly oil the grates to prevent the glaze from sticking.
Grill the skewers for 3 to 4 minutes per side, or until the pork is cooked through and the glaze is bubbly and dark.
Remove from heat and garnish the skewers with thinly sliced green onions and toasted sesame seeds.
Serve the skewers immediately alongside the chilled, sliced cucumbers for a refreshing and cooling crunch.