Preheat the oven to 350 degrees F. Line a baking sheet with parchment paper.
Pulse the onion, garlic and carrot pieces into a food processor until the texture is very finely diced. Set aside.
In a large mixing bowl, briefly stir together the ground beef and pork. Add in the processed onion, garlic and carrot mixture, ketchup, molasses, balsamic vinegar, parsley, gluten-free bread crumbs, and salt. Mix gently to combine. Form the mixture into balls about the size of golf balls. Place them on the lined baking sheet.
Bake the meatballs in the center of the pre-heated oven for about 30 minutes until no longer pink in the center. Allow meatballs to cool. Put meatballs into gallon-sized freezer bag, remove as much air as possible, label and freeze.
To serve: Thaw. Heat meatballs through to serve.