1.Combine pork, onion, ginger, gai lan, egg yolk and 2 teaspoons of the soy sauce in a medium bowl. Divide mixture between wrappers (1 heaped teaspoon per wrapper). Brush wrapper edges with water, fold in half and press edges to seal.
2.Line a bamboo steamer with a piece of baking paper; prick a few holes in paper. Place steamer over a large saucepan or wok of simmering water; steam dumplings, in batches, for 8 minutes.
3.Meanwhile, combine remaining soy sauce, sweet chilli and lime juice in a small bowl.
4.Serve dumplings with sweet chilli dipping sauce.
Dumplings are best made and cooked or you can freeze uncooked dumplings in a single layer on a tray, then place into airtight containers or snap-lock bags for up to 3 months. Steam straight from the freezer, just add 2 minutes to the cooking time. If sweet chilli sauce is too spicy for your toddler, use a mild sweet chilli or no sauce at all.