1. Using large chimney starter, ignite about 4 1/2 quarts charcoal, or about 65 briquettes and let burn until all charcoal is covered with layer of fine gray ash, about 15 minutes. Empty coals onto grill. Using long-handled tongs, divide coals in half to form two piles on either side of grill. Place 16 x 12-inch disposable aluminum roasting pan in center, between coal piles. Position cooking grate over coals, cover grill, and heat until hot, about 5 minutes; scrape grate clean with grill brush.

2. While grill heats up, combine soy sauce, sugar, ginger, and garlic in small saucepan; stir together mirin and cornstarch in small bowl until no lumps remain, then stir mirin mixture into saucepan. Bring sauce to boil over medium-high heat, stirring occasionally; reduce heat to medium-low and simmer, stirring occasionally, until sauce is reduced to 3/4 cup and forms syrupy glaze, about 4 minutes. Cover to keep warm.

3. Sprinkle chicken on both sides with salt and pepper. Place chicken skin side up in single layer on center of grill over roasting pan. Cover and cook until instant-read thermometer inserted into thickest part of thighs registers 170°F, 15 to 20 minutes. Flip chicken and move pieces to sides of grill, directly over coals. Grill until skin is browned and crisp, about 5 minutes, moving chicken back to center of grill if flareups occur.

4. Transfer chicken to cutting board; let rest 2 to 3 minutes. Cut meat crosswise into 1/2-inch-wide strips. Transfer chicken to serving platter; stir teriyaki sauce to recombine, then drizzle to taste over chicken. Serve immediately, passing remaining sauce separately.

Serves 4 to 6