*Japanese mayonnaise is available from the Asian grocery section of supermarkets or Asian grocery stores.
Place mushrooms, cabbage and prawn meat in large bowl.
Sift flour over mushroom and cabbage mixture and toss gently to coat evenly with flour. Add eggs, milk and water, stir gently to combine. Season with salt and pepper.
Heat barbecue plate to medium-high and drizzle with 2 tbs oil. Scoop ¼ cup measures of mushroom mixture onto the barbecue plate to form eight small pancakes. Barbecue for 2-3 minutes on each side until golden and cooked through. Transfer to a plate and keep warm. Repeat with remaining mixture.
To serve, top each pancake with a 1 tsp mayonnaise, drizzle with soy sauce and garnish with green onions.