In a large bowl, combine the ground chicken, panko, eggs, crumbled feta, minced red onions, sun dried tomatoes, dried dill, dried oregano, garlic powder, salt, lemon zest, and mint. Mix gently with your hands until just combined—avoid overmixing, which can make the meatballs tough and dense. The mixture should hold together when squeezed but still feel light and airy. I find that using my fingertips rather than my whole hand keeps the mixture tender and prevents the feta from breaking down too much.

Preheat your oven to 400°F. While it heats, shape the mixture into 15 equal-sized meatballs (about 1.5 inches each) using your hands or a small ice cream scoop for consistency. Heat the olive oil in a large oven-safe skillet over medium-high heat until shimmering. Working in batches if needed to avoid crowding, gently place the meatballs in the hot oil and sear for 2-3 minutes, turning occasionally, until golden brown on all sides. This browning step develops flavor and creates a light crust that helps the meatballs hold their shape during baking.

Transfer the skillet to the preheated 400°F oven (or transfer the browned meatballs to a baking sheet if your skillet isn't oven-safe) and bake for 22-25 minutes, until the meatballs are cooked through and a meat thermometer inserted into the largest one reads 165°F. Remove from the oven and let the meatballs rest for 2 minutes before serving—this allows the juices to redistribute and keeps them moist. I always let them cool for a minute or two because they're quite delicate when hot and benefit from that brief rest.

Transfer the meatballs to a serving platter or individual plates. Drizzle or dollop the tzatziki sauce over the top, or serve it on the side for dipping. Garnish with additional fresh mint if desired.