Preheat oven to 400°F. Line parchment paper with a baking sheet (no cooking spray or oil is required).
In a medium bowl, cover 8 oz dried bread slices with lukewarm water; let it stand and soak for few minutes. Squeeze out the water from bread and grate onto a large hole of grater.
In a large bowl, combine and mix 2 ½ lbs ground pork meat and grated bread (for best results, use your hands).
Grate 1 medium yellow onion onto a small hole of grater. Dispose any excess onion juice.
To the meat, add grated onion, ½ cup real mayo, 2 tsp fine salt and ½ tsp ground black pepper. (start with 2 tsp salt and add more if needed - depends on mayo brand). Mix well until everything is fully combined. (You are welcome to add more pepper if spicy meatballs are preferred).
Scoop meat with a small cookie scoop for equal sized meatballs. (Using cookie scoop will save time and it will help meatballs cook more evenly if they are the same size). Roll them in bread crumbs and slightly flatten each one to about ½″ thick. Transfer onto baking sheet (side by side). You will most likely need an additional smaller baking sheet to fit 10-15 remaining meatballs. Bake both baking sheets at the same time.
Bake for 40-45 minutes or until fully cooked, by flipping meatballs over halfway through. (I usually do 25 mins one side and 20 another).
Transfer baked pork meatballs into a dish and serve warm over a bed of mashed potatoes or pasta. Refrigerate or freeze leftovers once cooled.
