Step 1 Place rice into a small saucepan and add 1 1/2 cups water. Simmer, covered, for 10-15 minutes, or until cooked. Add corn and pea mixture in the last 2 minutes of cooking. Fluff with a fork and keep warm.
Step 2 Meanwhile, steam parsnips and carrots for 6-8 minutes, or until tender. Keep warm.
Step 3 Meanwhile, preheat grill and baking tray. Place flathead fillets onto a piece of foil and sprinkle with parmesan. Place foil and fish onto the hot baking tray and place under grill.
Step 4 Grill fish for 2-3 minutes (on one side only), or until cooked through and cheese is golden.
Step 5 Serve fish with rice mixture, parsnips and carrots, tzatziki and lemon wedges.