In a medium sized bowl, combine the finely diced red onion, turkey, oil, shawarma spice, and salt. Mix until well combined.

Roll out about 10 evenly shaped balls of turkey burger meat and shape them into patties. Place the patties on a large plate or baking sheet until ready to cook.

Heat a large non-stick skillet over medium heat. Grease with cooking spray.

Add about half of the patties to the pan, making sure they do not stick to each other. You will likely need to cook the burgers in 2 or 3 batches.

Cook on one side until the bottom turns brown. Do not try to flip the burger until the underside is brown and it lifts easily from the pan (if it sticks, it is not ready to flip).

Cook for about 5 minutes total, flipping halfway through to sear the other side of the burger. The patties are done when the internal temperature at the center registers 165ºF on a thermometer.

When the burgers are done, remove them from the pan and wipe out the pan with a clean towel.

Grease the pan and repeat steps 6-8 to cook the remainder of the burgers.

Assemble each burger on a whole wheat bun with baby spinach, 1 Tbsp of tzatziki sauce.