Prepare the chicken: Pat the boneless, skinless chicken thighs dry with paper towels. Cut them into bite-sized pieces, if desired, or leave whole for grilling.

Make the marinade: In a medium bowl, combine the minced garlic, minced ginger, gochujang, gochugaru, soy sauce, honey (or brown sugar), sesame oil, and water (or chicken broth). Whisk until well combined and smooth.

Marinate the chicken: Add the chicken thighs to the bowl with the marinade, ensuring each piece is thoroughly coated. Cover the bowl and refrigerate for at least 30 minutes, or ideally 2-4 hours, or even overnight for maximum flavor.

Cook the chicken: Heat 1 tablespoon of cooking oil in a large skillet or grill pan over medium-high heat. Add the marinated chicken, ensuring not to overcrowd the pan. Cook in batches if necessary.

Sear and cook through: Cook for 4-6 minutes per side, or until the chicken is cooked through, beautifully caramelized, and the internal temperature reaches 165°F (74°C). If grilling, cook over medium-high heat until done.

Serve: Transfer the cooked chicken to a serving plate. Garnish with sliced green onions and sesame seeds, if using. Serve immediately with steamed rice and kimchi for a complete Korean meal.