In a large bowl, mix together the breadcrumbs (1/2 cup), milk (1/2 cup), eggs (2), grated onion plus the juices, minced garlic (1 clove), dried oregano (2 teaspoons), kosher salt (1 teaspoon), and black pepper (1/2 teaspoon) until everything is uniformly wet.
Add the ground beef (2 lbs) and mix until everything is just combined. Try not to overwork it. Mixing with your hands is best, but you can use a spoon if you don't like handling raw meat.
Using a large cookie/ice cream scoop, scoop the meatball mixture onto a rimmed baking sheet (alternatively, you can form the meatballs with your hands).
Bake the meatballs in the center of the oven at 375 degrees F for 30 minutes, or until internal temperature is at least 160 degrees.
Serve the meatballs with sauce and grated parmesan cheese on top of pasta, in subs, in a salad, or however you like!
You can make small meatballs using a smaller scoop or forming them with your hands. If you do this, you may need two rimmed baking sheets and less baking time. I recommend baking for 20-25 minutes, and rotating the baking sheets from the bottom to top rack halfway through baking if both don't fit on the center rack.
To freeze, arrange cooked meatballs on a baking sheet or plate and place in freezer for about 30 minutes to flash freeze. Remove to a zip-top bag or airtight container and freeze for up to 4 months for best quality.
To use lean ground beef, I recommend coating the bottom of your baking sheet with a coat of olive oil to avoid sticking.
For easier clean-up, line your baking sheet with foil.