Whisk together gochujang, oil, soy sauce, honey, lemon juice and crushed garlic.
Pour 3/4 of the marinade/glaze over the chicken and rub in, making sure every piece is coated. Set the remaining marinade aside for grilling.
Cover and allow to marinate for at least 30 minutes but up to 24 hours in the fridge.
Grill the chicken over medium heat, brushing with the remaining marinade, until golden, caramelized and cooked through. Remove from the heat and allow to rest for 5 minutes.
Scatter the grilled chicken with sesame seeds and chopped spring/green onion and serve.