In a small saucepan, combine all of the Tsukune Sauce ingredients, mix well, and bring to a boil over high heat.
Reduce the heat to low and simmer until it is reduced by half. This may take about 20 minutes.
Tsukune Meatballs
Preheat the oven to 400 degrees. Line a baking sheet with foil and a little cooking spray.
In a large bowl, combine all ingredients and mix well with your hands.
Shape meat mixture into 6 oval shapes and place on baking sheet.
Bake for about 25 minutes, basting each meatball with ½ of the Tsukune Sauce after 15 minutes. Remove the meatballs from the oven when they reach an internal temperature of 160 degrees F using an instant-read meat thermometer. Baste the meatballs again with the remaining ½ of the sauce.
Press each skewer through a meatball until it’s two thirds of the way down the skewer. Serve immediately.