In a large mixing bowl, combine ground chicken, onion, garlic, parsley, cumin, paprika, salt, and pepper. Mix until well combined.
Divide the mixture into four equal portions and shape into burger patties.
Heat olive oil in a skillet over medium heat. Cook the patties for 4-5 minutes per side or until fully cooked (internal temperature reaches 165°F).
Lightly toast the burger buns in the same skillet or under a broiler.
Assemble the burgers: Place a patty on the bottom bun, add lettuce, tomato, red onion, and tzatziki sauce, then top with the other bun.