Make the Tare: In a medium saucepan, combine the brown sugar, mirin, and soy sauce. Mix well and simmer over low heat for 30 minutes until slightly thickened. Remove from heat and let cool. (Pro Tip: Char meat trimmings and green leek tops on the grill and add them to the simmering sauce for extra depth of flavor).
Preheat the Grill: While the tare simmers, preheat your grill to high heat (preferably using Binchotan charcoal).
Prep the Skewers: Thread your bite-sized pieces of protein tightly onto metal skewers, alternating with pieces of leek.
Trim & Season: Lay the skewers flat on a clean cutting board and trim the edges so the meat forms a uniform rectangular cylinder. Season all sides generously with kosher salt.
The First Grill: Place the skewers on the grill and cook until the protein is about 80% cooked through.
Dip and Lacquer: Remove from heat and dip the skewers directly into the tare (or baste heavily). Return to the grill for 30 seconds per side until the sauce tacks up and caramelizes. Repeat this process 1 to 2 more times to build a thicker glaze.
Garnish: Remove from the grill, sprinkle with Togarashi, and serve immediately.
