1.Shell and devein prawns, leaving tails intact. In a large bowl, combine prawns with beef, chicken, sauce, garlic and chilli; stand 15 minutes.
2.Meanwhile, make dipping sauce.
3.Discard mushroom stems; cut a cross in the top of caps.
4.On a heated oiled grill plate (or grill or barbecue), cook ingredients, except green onions, in batches, until vegetables are just tender, prawns and beef are cooked as you like, and chicken is cooked through.
5.Serve with green onion and individual bowls of dipping sauce.
6.In medium saucepan, stir ingredients until sugar dissolves.
You could use rump or sirloin steak instead of the beef eye fillet.Note