1.Preheat oven to 150ºC/130ºC fan-forced. Line a large baking tray with baking paper. Place a large wire rack on prepared tray.
2.Cut fish into 3cm-wide, long strips. Place fish, prawns, eggplant and beans on a large baking tray lined with paper towel. Pat dry. Heat oil in a wok or large deep-frying pan over medium-high heat. Place batter mixture into a medium bowl. Slowly add iced water, whisking constantly until smooth.
3.Working in batches, dip fish in batter to coat, allowing excess to drain off. Cook for 2 to 3 minutes or until golden and cooked through. Transfer to wire rack. Place in oven to keep warm. Repeat with remaining fish, prawns, eggplant, beans and batter. Arrange seafood and vegetables on plates. Serve with soy sauce.