Sheet Pan Meatballs with Chickpeas, Turmeric and Lemon

Name: Sheet Pan Meatballs with Chickpeas, Turmeric and Lemon
Cuisine: Middle Eastern
Ingredients: 2 (15-ounce) cans chickpeas, drained and rinsed; 1 tablespoon fennel seed; 1 teaspoon ground cumin; 1 teaspoon ground turmeric; 1 large red onion, thinly sliced, divided; 2 tablespoons olive oil; Kosher salt and freshly ground black pepper; 1 pound (455 grams) ground turkey; 1/2 cup panko, or another plain, dry breadcrumb; 1/4 cup plain yogurt; 2 tablespoons water; 1 teaspoon kosher salt; 1 large egg; 2 garlic cloves, minced; 1/2 teaspoon ground coriander; 1/2 teaspoon ground cumin; 1/2 teaspoon ground turmeric; 1/4 teaspoon cayenne, hot paprika, or red pepper flakes, plus more to taste; 2 tablespoons chopped cilantro, flat-leaf parsley or mint leaves, or a mix thereof, plus more to garnish; 3 tablespoons lemon juice (from about 3/4 of a lemon); 3/4 cup plain yogurt; Toasted pita wedges; Harissa or another hot sauce