Soak four wooden skewers in water for at least 20 minutes to prevent them from scorching on the grill.
Cut the pork tenderloin and pork belly into uniform 1-inch cubes.
In a small mixing bowl, whisk together the gochujang, tamari, honey, toasted sesame oil, minced garlic, and grated fresh ginger until smooth.
Thread the pork tenderloin and pork belly cubes onto the soaked skewers, alternating the pieces to allow the pork belly fat to baste the lean tenderloin.
Brush the skewers generously on all sides with half of the prepared gochujang glaze.
Heat a grill pan or outdoor grill to medium-high heat and lightly grease the grates.
Grill the skewers for 3-4 minutes per side, applying the remaining glaze during the final minutes of cooking until the meat is caramelized and cooked through.
While the pork rests, toss the sliced cucumbers with rice vinegar, red pepper flakes, and sesame seeds.
Serve the hot, spicy skewers immediately alongside the refreshing cucumber salad for a balanced, high-protein meal.