While the meatballs are baking, you can make the sauce. In a medium saucepan or skillet over medium heat, combine all ingredients (except the butter) together. Remove from heat and whisk in the butter to create a silky smooth finished sauce. Return to heat and add a cornstarch slurry: In a small bowl, whisk together the cornstarch and cold water until smooth. While whisking, slowly pour the cornstarch slurry into the simmering sauce. Continue to cook, stirring frequently, for 1-2 minutes, or until the sauce thickens and becomes glossy.
1/4 cup soy sauce, 2 Tbsp. butter, unsalted , 1/4 heaping cup honey, 2 Tbsp. Sriracha (more or less to taste), 1 Tbsp. sesame oil, 1 Tbsp. rice vinegar, 1 tsp. ginger (minced if using fresh or ginger paste), 3 cloves minced garlic or pressed in a garlic press