Turn on the slow cooker to low heat and add the meatballs so they can begin thawing.

Add the balsamic vinegar, Frontera Merlot, garlic, soy sauce, and honey to a saucepan over medium-low heat and bring to a boil.

Reduce the heat to low and simmer for 20 to 25 minutes.

Then add the cubes of butter to the mixture, stirring constantly to thicken as the butter melts.

In a small prep dish, stir together the corn starch and water until starch dissolves, then stir into sauce.

Cook for another 2 to 3 minutes, stirring constantly, then pour sauce over the meatballs in the slow cooker.