Preheat oven to 425 degrees F. Gather & prep all ingredients.
Combine all listed glaze ingredients in a medium saucepan over medium-high heat. Bring the mixture to a boil, then reduce heat to maintain a steady simmer. Cook, stirring frequently, until reduced by half. The resulting reduction will be a pretty thick & glossy glaze. Remove from the heat & set aside.
Add the turkey, egg, panko, green onions, ginger, & garlic to a mixing bowl. Season with S&P. Using your hands, mix just until combined – take care to avoid over-mixing. Use a large scoop to form 12 turkey meatballs, each roughly 2-3 inches in diameter. Using your hands, roll the meatballs just until smooth. Set aside.
Add the grapeseed oil to large, oven-safe skillet over medium-high heat. Once the skillet is hot & the oil is shimmering, carefully add the meatballs to the skillet. Cook 2 minutes until bottom of meatball is browned & crusty, then flip & cook 2 minutes longer. Repeat once more, searing meatballs for 6 minutes total.
Carefully pour half of the ginger-soy glaze into the skillet over the meatballs, shaking to coat. Transfer to the oven & bake for 5-7 minutes, shaking halfway through, until meatballs are cooked through with an internal temperature of 165 degrees F.