In a medium bowl, combine the cornstarch with the water.
Whisk in the brown sugar, soy sauce, honey, ginger, and garlic powder.
Add the sauce to a small sauce pan and bring the sauce to a simmer over medium-high heat.
Reduce the heat to medium and cook until the sauce has thickened enough to coat the back of a spoon, about 5 minutes.
The sauce will continue to thicken as it cools.
