Slice the pork belly and pork tenderloin into uniform 1-inch cubes.
In a medium bowl, whisk together the gochujang, tamari, honey, grated ginger, and minced garlic.
Add the pork cubes to the bowl and toss until every piece is thoroughly coated in the spicy marinade.
Thread the pork onto wooden or metal skewers, alternating between the belly and tenderloin pieces.
Heat a grill pan or outdoor grill over medium-high heat and lightly coat with a mist of oil.
Grill the skewers for 3-4 minutes per side until the pork is cooked through and the edges are beautifully charred.
While the pork cooks, toss the sliced cucumbers with rice vinegar in a small bowl for a quick pickle.
Serve the hot skewers immediately alongside the chilled cucumber salad, garnished with sesame seeds and sliced green onions.