Soak four wooden skewers in water for at least 20 minutes to prevent burning.
Cut the pork tenderloin and pork belly into uniform 1-inch cubes and place them in a medium bowl.
In a small jar, whisk together the gochujang, coconut aminos, honey, rice vinegar, sesame oil, minced garlic, and grated ginger until smooth.
Pour half of the gochujang mixture over the pork cubes, tossing well to coat; reserve the remaining sauce for glazing.
Thread the pork onto the soaked skewers, alternating between the lean tenderloin and the rich pork belly pieces.
Preheat a grill or cast-iron grill pan over medium-high heat and lightly grease with a high-smoke point oil if needed.
Grill the skewers for 3 to 4 minutes per side, or until the pork is cooked through and develops a deep, caramelized char.
During the last 2 minutes of grilling, brush the reserved gochujang glaze generously over all sides of the meat.
Thinly slice the cucumber and scallion, then toss the cucumber with a pinch of sea salt.
Remove skewers from the heat and garnish with sesame seeds and sliced scallions before serving with the chilled cucumber salad.