Get yourself a deep flat bowl that will fit into your steaming pot and then add in your chopped chicken thighs, minced ginger, lemongrass, garlic, pinch of salt, grind of pepper, sugar, soy sauce, and olive oil. Give everything a really good mix. It should smell very aromatic and delicious already!
Put a circular rack or a small, heatproof bowl upside down at the bottom of a large saucepan or pot with a lid. Carefully pour boiling water into the pot until it reaches about three-quarters of the way up the sides of the rack or bowl. This setup will keep whatever you're steaming elevated above the water level.
Place your chicken bowl into the pot on top of your steaming implement and add the lid onto your pot. Place on medium heat and steam for 15 minutes.
Meanwhile, place all of your sauce ingredients into a blender and blend until smooth. Taste and season accordingly.
After 15 minutes, carefully remove the steamed chicken from the pot, or you can leave it in there if it's too hot and serve from there.
Ladle the steamed chicken juices out of the bowl and into a separate bowl. Add 2-3 tablespoons of the coriander sauce (more or less depending on your spice tolerance). Give it a mix and taste and adjust.
Serve up your steamed chicken with rice and then pour over your coriander sauce. Top with spring onions and enjoy!