Step 1

If using wooden skewers, place 6 in water and let soak while you prepare the tsukune.

Step 2

Place 1 1/4 cups soy sauce, 3/4 cup mirin, 1/2 cup sake, and 2 tablespoons packed brown sugar in a small saucepan. Bring to a simmer over medium-high heat, stirring constantly, until the sugar is dissolved. Continue to simmer, stirring frequently, until reduced by half (about 1 1/4 cups), syrupy, and thick enough to coat the back of a spoon, 10 to 12 minutes.

Step 3

Line a rimmed baking sheet or plate with aluminum foil.

Step 4

Prepare the following, adding each to the same large bowl as it is completed: Finely chop 2 to 4 medium scallions until you have 1/3 cup. Peel and finely grate 3 large garlic cloves (about 2 teaspoons). Peel and finely grate a 1/2-inch piece of ginger until you have 3/4 teaspoon.

Step 5

Add 1 pound ground chicken, 1 large egg, 1/3 cup panko breadcrumbs, 1/2 teaspoon toasted sesame oil, 1/4 teaspoon kosher salt, and 1/4 teaspoon ground white pepper. Vigorously stir with a wooden spoon or flexible spatula until light, airy and paste-like in texture, 2 to 3 minutes.

Step 6

With damp hands, shape and roll the mixture into 18 (1-inch) meatballs. Place on the foil, arranging them in rows of Insert a skewer through each row of meatballs, skewering through the center of each and leaving a little space between each one.

Step 7

Refrigerate for 15 minutes to let the meatballs firm up and the breadcrumbs rehydrate. Meanwhile, heat an outdoor grill to medium-high, direct heat (about 425ºF). If you’re using a grill pan on the stovetop, wait until the meatballs are chilled before heating to medium-high heat.

Step 8

Scrape the grill grates clean if needed. Oil the grill grate with a paper towel dipped in vegetable oil. Lightly coat the tops of the meatballs with cooking spray. Place the skewers with the meatballs oil-side down on the grill grates. Cover and grill undisturbed until browned on the bottom and they easily release off the grill grates, 3 to 4 minutes. Meanwhile, discard the foil.

Step 9

Flip the skewers and continue grilling, turning them every few minutes, until well browned all over, cooked through, and an instant-read thermometer inserted into the center of a meatball registers at least 165ºF, 6 to 7 minutes more.

Step 10

Brush the meatballs with a thin layer of the sauce (save the remaining sauce for grilled fish, yakitori, or more tsukune). Grill uncovered for 15 to 20 seconds more. Return to the baking sheet or plate, brush the other sides of the meatballs with more sauce, and let rest for 3 minutes before serving.