Preheat oven temperature to 350 degrees F. Prepare rimmed baking sheet lined with parchment paper.
Add onion to a food processor and pulse until minced, then add remaining meatball ingredients and pulse until ingredients are fully combined and looks like a paste. Using a small ice cream scooper or grab golf ball sized meat mixture to make meatballs and transfer onto parchment lined baking sheet. Gently press to shape any loose meatballs. Space them evenly about an inch apart. Bake for 10-12 minutes (it will cook further in the sauce).
Meanwhile, prepare the sweet and sour sauce. Set a pot (large enough not to splatter) on medium-high heat then add marinara sauce, chicken broth, passion fruit juice, and coconut amino, bring to a boil. When boiling, add honey, apple cider vinegar, dijon mustard, ground ginger, and salt. Reduce heat to medium. When the meatballs are ready, add them to the sauce (discard the liquid remaining) and continue to cook another 20 minutes, covered.
The sauce and meatballs can be made up to 3 days in advance. If using pineapple juice in the sauce, do not add to the sauce. Store them separately to prevent the pineapple enzymes from breaking down the meat. Before serving: combine and reheat on low heat.
For freezing ahead: Cool sauce and meatballs completely (should not be even the slightest warm) then store each separately, in an airtight freezer-safe container, and freeze for up to 3 months. Thaw in the refrigerator overnight, then transfer into a pot and reheat on the stove at low heat or in a 300 degree F oven for 20-30 minutes, until heated through.
Recipe by From Jessica's Kitchen at http://fromjessicaskitchen.com/sweet-and-sour-meatballs-over-cabbage-a-modern-take-on-stuffed-cabbage-dairy-free-gluten-free-nightshade-free-paleo-friendly-soy-free/