Working in three batches; place the tuna, pine nuts, parsley and onions in a food processor and pulse about 8 to 10 times to combine, but not puree. Transfer the mixture to a large bowl and add the eggs, breadcrumbs, salt + pepper and lemon zest. Gently mix with your hands to combine well.
Use an ice cream scoop to portion the meatballs, then form with your hands and place on a parchment lined sheet pan. You should get about 20 to 25 meatballs, depending on the size of your scoop.
Dust the meatballs with the flour in a shallow dish, then place them back on the sheet pan.
Heat ½" canola oil in a frying pan until it is 350 degrees. Fry 6-8 meatballs at a time until browned on each side and cooked through, about 15 minutes. Place on a paper towel lined sheet pan to drain off any excess oil.
Heat the tomato sauce in a separate pan and stew the meatballs for about 5 minutes to warm through.
Serve with pasta and tomato sauce.
Recipe inspired by Hank Shaw @ Hunter Angler Gardener Cook