Wash and cut the Choy sum into 2 inch size pieces. Cube the tofu in to bite size cubes, around 1 inch squares. Quarter the mushrooms (if using).

Peel, wash and de - vein the shrimp.

Make the sauce. - Add all the sauce ingredients into a bowl, and stir so that the cornflour has dissolved.

Heat the wok until it is smoking. Add a tablespoon of vegetable oil to the wok.

As soon as the wok is hot, add the Choy sum and any other green vegetables and mushrooms, and stir until cooked. Whilst stirring, add the ginger, garlic and chili's, if using. Keep stirring the vegetables to distribute the heat. They should have a slight bite to them, and not be over cooked.

Then add the shrimp and bean sprouts, again, keep stirring the ingredients in the pan, until you see the shrimp start to turn pink. Then add the sauce and stir in to the ingredients in the pan. Once you see the sauce start to bubble, very carefully add the tofu if using, and gently stir so the tofu is nicely distributed. Fresh tofu is very delicate and will break up easily, so be gentle! Once the sauce begins to bubble, it's done!

Serve hot from the pan with some nice fragrant jasmine rice.