Recipe adapted from Serious Eats.
Makes 8 baseball sized meatballs
1 lb ground beef, 75% lean
1 cup bread crumbs
1/2 of medium onion
1/3 c milk
3 T vinegar or white wine
4 cloves garlic, finely chopped
1 oz Parmigiano-Reggiano, grated plus more for serving
2 T dried parsley
2 t sea salt or kosher salt
1/4 t dried oregano
1/4 t fennel seeds
Set oven rack in the uppermost position and preheat broiler setting on low. Line a baking sheet with tin foil.
In a large bowl place everything in it. Use both your hands to mix the ingredients. Form into baseball sized meatballs; smaller-if you prefer.
Set each meatball on the prepared baking sheet making sure they're not too close from each other.
Broil meatballs until browned on top; about 7 minutes or so. Browning times vary depending upon the strength of your oven broiler.
Take out from oven and flip each meatball using a tong. Place back in oven to broil that side facing up. At least 7 minutes again-more or less.
If using in a spaghetti like I did above, simmer in the pasta sauce of your choice for 10 minutes.