First make the Black Bean sauce: deseed the chilli then finely chop; rinse the black beans are washed and drain; mince the garlic Add all ingredients to a small blender and whiz until you get a coarse mixture. Set aside.
Peel the ginger and cut it into matchsticks.
Heat the oil in a wok. When it begins to smoke, add the ginger, stir-fry for a few seconds, then throw in broccoli, add a drop of water and stir-fry for 2 minutes.
Add the mushrooms, gently stir-fry, making sure they don’t break up.
After 2 minutes, stir in the bean sauce and add the stock. Cook for 3 minutes.
Add soy sauce to your liking, then thicken it with the cornflour-water mixture. This should take a couple of minutes.
Serve hot.