Start by finely chopping the onion, garlic, and fresh herbs. Gather all ingredients.

In a large mixing bowl, combine the ground chicken, chopped onion, garlic, feta, fresh herbs, dried oregano, salt, black pepper, red pepper flakes, lemon zest, lemon juice, breadcrumbs, and egg. Mix gently until combined.

Divide the mixture into equal portions and shape each into patties about ¾ inch thick. Refrigerate for 30 minutes if possible.

For grilling, preheat grill to medium-high and cook patties for 6-7 minutes each side. For pan-searing, heat olive oil in a skillet and cook for 5-6 minutes per side.

For baking, preheat oven to 375°F and bake patties for 20-25 minutes until golden-brown. For air frying, preheat air fryer and cook for 12-14 minutes, flipping halfway.

Prepare the tzatziki sauce by mixing Greek yogurt, grated cucumber, minced garlic, lemon juice, and chopped dill in a bowl. Season with salt.

Assemble each patty on a bun or pita, topping with tzatziki sauce and fresh vegetables.