Heat the oven to 425°F (220°C). Place a rimmed baking sheet in the oven to preheat.
In a large bowl, combine turkey, grated onion (and its juices), garlic, egg, breadcrumbs, parsley, dill, oregano, salt, pepper, lemon zest, and olive oil.
Use a fork or your hands to mix until just combined. Do not overmix or the meatballs will turn dense.
Lightly oil your hands. Scoop 2-tablespoon portions and roll into balls. You should get about 22–24 meatballs.
Set them on a plate while the baking sheet heats fully.
Carefully remove the hot baking sheet and line it with parchment or brush with oil.
Arrange meatballs with a little space between them.
Bake for 12–15 minutes, until the centers reach 165°F (74°C).
For extra color, broil for 1–2 minutes at the end. Watch closely.
While the meatballs bake, stir together yogurt, squeezed cucumber, garlic, lemon juice, olive oil, dill, salt, and pepper.
Taste and adjust with more lemon or salt. Chill until serving for best flavor.
Plate meatballs with a generous spoonful of tzatziki.
Add pita, salad, tomatoes, red onion, and olives. Finish with a squeeze of lemon.
