Pat the chicken thighs dry. Coat each thigh generously with liquid shio koji—about 1 tablespoon per thigh, spread evenly on all surfaces.
Place the thighs in a resealable bag or container and refrigerate for a minimum of 4 hours, ideally 12–24 hours.
When ready to cook, remove the thighs from the bag and gently pat off excess moisture.
Grill method: Preheat your grill to medium-high. Oil the grates. Grill thighs 4–5 minutes per side until cooked through (165°F internal) with good char marks.
Pan-sear method: Heat oil in a cast iron or heavy skillet over medium-high heat. Sear thighs presentation-side down for 4–5 minutes until deeply golden. Flip and cook another 3–4 minutes until cooked through.
Rest the chicken for 5 minutes, then slice on the bias into ¼-inch strips for ramen.
