Fritto Misto With Fennel And Lemons

Name: Fritto Misto With Fennel And Lemons
Ingredients: Vegetable oil, for frying; 2 1/2 cups all-purpose flour; 1/2 cup cornstarch; 1/2 teaspoon baking powder; Kosher salt and freshly ground black pepper; 2 cups club soda; 12 large shrimp, shelled and deveined; 3/4 pound skinless cod fillet, cut into 12 chunks; 1/2 pound squid, tentacles halved and bodies sliced into 1/2-inch rings; 1 small fennel bulb, sliced lengthwise 1/8 inch thick; 1 lemon, very thinly sliced, plus lemon wedges for serving; 1/4 cup coarsely chopped flat-leaf parsley leaves