Preheat the oven to 400°F (200°C) and lightly grease a baking sheet with the tablespoon of olive oil.
In a large mixing bowl, combine the ground chicken, breadcrumbs, egg, chopped red onion, minced garlic, crumbled feta, parsley, mint, dried oregano, lemon zest, salt, and black pepper.
Mix gently until just combined, taking care not to overwork the meat so the meatballs stay tender.
Form the mixture into meatballs about 1½ inches (3.8 cm) in diameter using your hands or a cookie scoop, and place them on the prepared baking sheet, leaving space between each.
Bake for 15–20 minutes, or until the meatballs reach an internal temperature of 165°F (74°C) and are cooked through.
Remove from the oven and let the meatballs rest for a few minutes before serving.