In a large bowl, combine the ground chicken, panko breadcrumbs, red onion, garlic, parsley, mint, oregano, cumin, salt, and pepper. Mix gently until combined.

Incorporate the egg into the mixture, stirring until evenly distributed.

Shape the mixture into 1 to 1.5-inch meatballs, aiming for uniform size.

Heat olive oil in a skillet over medium heat. Add meatballs in batches and cook for 4-5 minutes on each side until golden-brown and cooked through.

Remove meatballs from the skillet and drain on a paper towel-lined plate.

In a separate bowl, combine Greek yogurt, cucumber, garlic, lemon juice, olive oil, dill, salt, and pepper. Mix well.

Cover and refrigerate tzatziki for at least 15 minutes.

Serve meatballs on a platter with tzatziki in the center.