Falafel Fritters Bowl with Cucumbers and Yogurt Sauce

Name: Falafel Fritters Bowl with Cucumbers and Yogurt Sauce
Ingredients: 2 15-ounce cans chickpeas, drained; 1 large egg; 2 tablespoons cornstarch; 2 teaspoons ground cumin; ¼ cup finely chopped parsley, plus 1 cup whole leaves with tender stems; ¾ cup plain whole-milk Greek yogurt, divided; Kosher salt, freshly ground pepper; 1 medium red onion; 8 tablespoons olive oil, divided; 2 tablespoons fresh lemon juice (from about ½ lemon), plus wedges for serving; 4 Persian cucumbers or ½ English hothouse cucumber, cut into 1-inch irregular pieces