Grate the zucchini using a box grater and place it in a clean kitchen towel; squeeze firmly to remove as much moisture as possible.
In a large mixing bowl, combine the ground beef, ground pork, egg, squeezed zucchini, sea salt, black pepper, garlic powder, onion powder, and chopped fresh parsley.
Gently mix the ingredients by hand until just incorporated, taking care not to over-compress the meat which can lead to a tough texture.
Portion the mixture and roll into 8 to 10 uniform meatballs, roughly the size of a golf ball.
Heat the avocado oil in a large cast-iron or non-stick skillet over medium-high heat until the oil shimmers.
Carefully place the meatballs in the skillet, ensuring they are not crowded to allow for proper browning.
Sear the meatballs for 4-5 minutes per side, turning carefully with tongs, until a deep golden crust forms and the internal temperature reaches 160°F.
Remove from the heat and let the meatballs rest for 2 minutes before serving to allow the juices to redistribute.