A friend just came back from Singapore raving about Singapore Chilli Crab. But I wasn't about to go hunting for the appropriate crabs, so I just tossed in some soft shell crab. But shrimp would also work great for this recipe. —Snafu06
If your store doesn't clean the crabs, the first thing you have to do is open up the shell at the belly and remove the yellow gills. Cut off the back flap and the face. Rinse inside and out and blot dry.
Dredge the crabs in the flour and shake off the excess, set aside.
Add oil to a large skillet and heat over medium heat until just shimmering.
Mix the ketchup, chili sauce, water, lime juice, and corn flour in a bowl.
Add the crabs and saute 2 minutes just until shell starts to redden. Flip and repeat. When both sides are tinged red, then remove.
If the skillet is dry, add another tablespoon of oil. Add ginger, garlic, serranos, and onion and saute until fragrant.
Add the ketchup mixture and bring to boil Quickly stir in the egg and continue stirring until the egg is well integrated. Not long, maybe a minute.
Add the crab and spoon the sauce over them, making sure they're coated. Reduce to a simmer and cook another minute more.
Serve! If you have a crusty bread, it makes a great accompaniment for the sauce.