• Whisk together soy sauce, onion, honey, gochujang, garlic, mirin, sesame oil, ginger and black pepper in a large bowl until combined. Add chicken and toss to coat; cover and refrigerate for at least 2 hours, ideally 4 hours, or up to overnight.

Grill method

• Heat a grill to high. Brush grill grate clean; brush grate with grapeseed oil to coat. Working in batches if needed, arrange sliced chicken on grill grate and cook just until cooked through and browned, about 1½ minutes per side.

Stove-top method

• Heat a cast-iron grill pan or cast-iron skillet over medium-high for 5 minutes. Brush pan with grapeseed oil and, working in batches, arrange chicken in a single layer in pan, making sure not to over crowd. Cook chicken until charred and just cooked through, 1½–2 minutes per side; transfer to a serving platter. Repeat cooking process with remaining chicken.

Optional

• Reserve the marinade and transfer to a small saucepan. Bring mixture to a boil over medium-high heat; cook until slightly thickened, about 3 minutes. Serve sauce with bulgogi.
• Serve chicken bulgogi with rice, butter lettuce cups, kimchi, scallions, sesame seeds, and ssamjang, if desired.