Thinly slice spring onions, keeping white ends and green tops separate. Place mince, ginger, sauces, oil, egg yolks and whites of spring onion in a large bowl and mix well to combine.
Line a large baking tray with baking paper. Working in batches, lay wrappers on a clean work surface. Place 1 tsp pork mixture in centre of wrapper. Moisten edge of wrapper with a little water, then fold in half to enclose filling, removing all air pockets. Pleat edge to seal, then place on tray. Repeat with remaining wrappers and filling, ensuring dumplings don't touch.
Bring a large saucepan or wok of water to the boil. Line a large bamboo steamer with baking paper. Steam dumplings in 4 batches for 8 minutes or until cooked through. Serve with extra soy and green onion tops.
Dumplings can be frozen prior to cooking. Place on a baking tray and freeze until firm. Once firm, transfer to an airtight container and freeze for up to 3 months. Increase cooking time to 12 minutes for each batch when cooking from frozen.