Make the sesame-citrus sprinkle :
- Mix sesame seeds, chives, Aleppo-style pepper, and lemon zest in a small bowl to combine; season with salt.
Make the chicken kebabs :
- Combine brown sugar, mirin, soy sauce, and vinegar in a small saucepan.
- Transfer 1/4 cup mixture to a large resealable plastic bag.
- Working one at a time, slice chicken thighs in half lengthwise.
- Add to bag with marinade and massage marinade into chicken.
- Chill at least 2 hours or up to 12 hours.
- Meanwhile, bring remaining marinade to a simmer over medium-high heat and cook until reduced by half and slightly thickened (just shy of syrupy), 8–10 minutes.
- Remove glaze from heat.
- Prepare a grill for medium-high, indirect heat (for a charcoal grill, bank coals on one side of grill; for a gas grill, leave one or two burners off).
- Oil grates.
- Thread chicken onto 6–8 skewers, folding and piling onto itself to form a compact shape.
- Season lightly with salt and grill over direct heat, turning every minute or so, until browned and beginning to char in spots, about 4 minutes.
- Move to cooler side of grill and continue to grill, basting lightly with glaze and turning every 30 seconds or so, until cooked through and coated with glaze, about 5 minutes longer.
- Serve chicken topped with sesame-citrus sprinkle.
- Do Ahead
- Glaze can be made 12 hours ahead.
- Let cool; cover and chill.
- Bring to room temperature before using.