1. Prepare the crabs. Snap the top, remove the stomach and gills, then chop the crabs in pieces, rinse the shell, gently smash the claws with a blade, coat the crab in corn starch.
2. Smash garlic; cut ginger in thick slices, keeping the skin on; cut scallions into sections; mix oyster sauce, sugar, dark soy sauce, corn starch and chicken stock to make a seasoned corn starch mixture.
3. Add oil in a heated wok, sauté ginger slices until they shrink and turns golden brown, add garlic and white part of scallion, sauté until fragrant, then remove ingredients from wok.
4. Reheat wok, add oil, sear the crabs, remove when they are half-cooked.
5. Return ginger, scallion and garlic to wok, add crab claws, sauté, add half of the green section of scallion, drizzle with Shaoxing wine, cover lid and cook for a while; when the claws are half cooked, add the rest of the crabs and sauté, add the remaining scallion and a little chicken stock, mix well.
6. When the sauce thickens slightly, remove the shell, then add the seasoned corn starch mixture, sauté until liquid dries up and the crabs fragrant; return the shell in wok, mix well and serve.