1. In a large mixing bowl, combine ground chicken, feta cheese, red onion, garlic, oregano, lemon zest, salt, and pepper. Mix gently until all ingredients are evenly incorporated.
2. Form the mixture into four equal patties, about 1/2 inch thick. Let them rest for a few minutes while you prepare the grill or skillet.
3. Heat olive oil in a large skillet over medium heat, or preheat your grill to medium-high.
4. Cook the patties for about 5-6 minutes on each side, or until they reach an internal temperature of 165°F. They should be golden brown and juicy.
5. Lightly toast the burger buns on the grill or in a toaster for extra flavor and texture.
6. Assemble the burgers by placing a patty on the bottom half of each bun, followed by a handful of arugula, a slice of tomato, and a generous dollop of tzatziki sauce. Top with the other half of the bun.

Cooking these burgers always reminds me of the time I spent helping my abuela in the kitchen. Just like her, I trust my senses to guide me, looking for that perfect golden sear and inhaling the fragrant mix of spices and herbs.