In a large bowl, whisk the eggs and lemon juice. Add the lemon zest, breadcrumbs, garlic powder, onion powder, za’atar, and salt and pepper and whisk with a fork to combine.
Add the tuna, spinach, and feta cheese and mix with a fork until well combined. Form the mixture into golf ball sized balls.
Heat a large skillet over medium high heat. Add enough avocado oil to coat the bottom of the pan in a thin layer. When the oil is hot, carefully place a few tuna balls in the pan. Cook for about 3-4 minutes on each side, until golden brown.
Remove from the pan and let cool slightly before serving with tzatziki or otherwise as desired.