Preheat the oven to 400°F with a rack in the center position.
Add the grated onion to a thin kitchen towel or nutbag. Gather the towel around the onion and squeeze out as much liquid as possible over the sink.
In a large bowl, combine the ground chicken, eggs, breadcrumbs, milk, garlic, grated onion, salt, turmeric, cinnamon, cumin, paprika, garlic powder and onion powder.
Mix well, then with wet hands, form meatballs (about 2 tablespoons each) and arrange on an oiled, rimmed baking sheet pan. You should have about 24 meatballs.
Arrange the red onion and bell peppers on the sheet pan between the meatballs. Brush the meatballs and vegetables with olive oil.
Bake until the internal temperature of the meatballs reaches 165°F on an instant-read thermometer, about 20 minutes.
Sprinkle with fresh parsley and serve with hummus, tzatziki, tahini sauce, pita, and cucumbers alongside.