Step 1 Preheat oven to 200ºC. Line a large baking tray with non-stick baking paper. Set aside.
Step 2 In a large bowl, combine potato, salmon, onion, zucchini, carrot and lemon zest. Using your hands, shape the mixture into 8 x 2cm thick fish cakes. Cover and refrigerate for 30 minutes to firm.
Step 3 Whisk together egg and milk in a shallow bowl. Place flour and breadcrumbs into 2 separate shallow dishes. Dip each cake in flour to coat, egg and then breadcrumbs. Repeat with remaining fish cakes.
Step 4 Place cakes onto tray and spray with oil. Bake for 20–25 minutes, turning once, until golden brown and crisp. Serve with a green salad and lemon wedges.