To make ahead: Freeze wontons, uncooked in single layer on waxed paper lined baking sheets until firm. Transfer to airtight container. Store in freezer for up to 2 months. Wontons can be deep fried frozen.
Stir water into cornstarch in small dish. Set aside.
Lay 1 wrapper on work surface with 1 corner closest to you. Keep unused wrappers covvered with damp tea towel to prevent drying out. Place 1/2 tsp filling in centre of wrapper. Brush adjacent edgesof wrapper with cornstarch paste.
Fold up 1 corner to meet oppostite corner, forming triangle. Plress edges together very firmly to seal. Brush opposite corners with cornstarch paste.
Bring opposite corners together under filling. Press together firmly. Repeat with memaining filling and wrappers, keeping filled wontons covered with damp tea towels.
Deep fry a few at a time, in hot (375degree) cooking oil until crisp and golden brown. Remove to paper towels to drain. Makes about 84 wontons.