Defrost the shrimps 2 hours before you are ready to cook. Pat dry to remove any water.
In a pan, put 1 tablespoon of oil. Once it is hot place the shrimps, making sure not to overcrowed the pan, you want to cook both sides just until golden brown, not fully cooked. Place aside on a plate.
With the same pan or wok, add the other 1 tablespoon of oil, add the diced onions, crushed garlic, and 2 pieces of thinly sliced ginger. Cook until the onions are a bit translucent. Add the ketchup, vinegar, Worcestershire, sugar, and water. Taste to see if more sugar is needed, and adjust the water depending on how thick you want the sauce to be. Add the shrimps back into the pan until cooked about 2-3 minutes depending on the size. Garnish with green onions and serve.
Let's talk about the shrimps, traditionally the shrimps are de-veined but shell on. Keeping the shell on adds flavor and prevents the shrimp from being overcooked. The shrimps that I used are 16-20.This recipe can serve 4 if you have other dishes with it, like we usually do in Chinese families. If not you can serve 2 if you have one vegetable side dish.