- In a medium bowl, stir together the soy sauce, brown sugar, scallions, vinegar, maple syrup, chile paste, sesame oil, ginger, sesame seeds, garlic, salt, and a generous amount of pepper until the sugar has dissolved. Transfer 1 cup of the marinade to a container, cover, and refrigerate. Add the chicken to the bowl with the remaining marinade and toss to coat. Cover and let marinate in the refrigerator, tossing once or twice, for at least 4 hours or up to overnight.
- Before grilling, let the chicken come to room temperature, about 30 minutes. Meanwhile, put the reserved 1 cup marinade in a small saucepan and simmer until it has thickened to a glaze-like consistency, 8 to 10 minutes; set the glaze aside.
- Preheat a gas or charcoal grill to medium-high heat.
- Lightly brush the grates with vegetable oil. Shake any excess marinade off the chicken and arrange on the grill without crowding. Grill, flipping the thighs halfway through, until cooked through, about 15 minutes. Keep an eye on the temperature; if the grill is too hot, the outside of the thighs will burn before the inside is done. Transfer the chicken to a platter and brush very lightly with the glaze. The glaze can also be served on the side as a dipping sauce, along with the Doenjang Mayonnaise.
In a small bowl, whisk together the mayonnaise and soybean paste until smooth. Cover and store in the refrigerator if not using immediately.
TIP: If you prefer boneless skin-on chicken thighs and can’t find them in the grocery, ask your butcher to debone skin-on thighs or simply use bone-in ones and just add a few minutes to the cooking time.