Mix chicken with brown sugar, 1 tablespoon of Savory Seasoned Salt, and 2 tablespoons of olive oil in a large bowl. Let sit for 30 minutes on the counter or up to 6 hours in the refrigerator.
Heat oven to 450°F.
Mix sliced bell peppers, Korean long peppers, pepperoncinis, chickpeas, garlic, and red onion wedges with 2 tablespoons of olive oil and 1 tablespoon of Momofuku Savory Seasoned Salt on a sheet pan. Top with prepared chicken. Pour Momofuku Rice Vinegar over the entire sheet pan, being careful not to rinse the seasoning off your chicken. Top each piece of chicken with a generous pinch of Momofuku Savory Seasoned Salt, then roast for 30 minutes or until the internal temperature of the chicken is 165°F.
Remove chicken from the pan and let it rest. Turn the broiler to high. Toss your vegetables gently then broil for 2–3 minutes until they start to char. Remove from the oven and stir in butter and soy sauce, scraping up browned bits on the sheet pan. Add chicken back to the sheet pan, then toss to evenly coat with sauce.
Serve topped with curly parsley, if desired, being sure to spoon pan sauce over chicken and vegetables.
