In a small bowl, whisk together the oyster sauce, soy sauce, sugar and water. This is your sauce mixture.
Chop the green onions and cilantro leaves and then set aside. You will be using this as garnish.
Once you start making this dish, things will have to come together very quickly, so make sure you have the rest of your ingredients at hand.
Heat butter in a large wok. You’ll want a wok with a lid of some kind.
When hot, lower the heat to medium and add chilis, ginger paste and garlic paste. Remember that it will sputter because the ginger and garlic pastes contain water. I use the lid of a pot as a shield and would suggest you use one as well.
Add coriander powder and half of the black pepper. Stir fry for 45 seconds.
Then add the sauce mixture.
Add the crab followed by 1.5 cups water.
Close the wok with the lid and keep on medium high heat for 10-12 mins.
Stir frequently and add water if the mixture is getting dry.
The crab legs will be fully warm when ready. Garnish with cilantro leaves and spring onions!