Soak water spinach in plenty of water to loosen up any dirt. Rinse under running water then drain well.
Trim off the ends of the stems if they appear to be hard. Then cut the vegetable into bite-sized sections. Separate the stems from the leafy part.
Mix the seasonings
Put fermented tofu, Shaoxing rice wine, salt and sugar into a small bowl. Use the back of a spoon to mash the fermented tofu. Mix everything to a smooth consistency.
Stir-fry the dish
Add oil to a wok. Fry minced garlic and fresh chilli over high heat. Once intense bubbles appear, pour in the seasoning mixture.
Add the stem part of the water spinach. Toss to fry for 20 seconds or so. Put in the leafy part, along with 1 tablespoon of water. Continue stir-frying.
When the leaves start to wilt, dish out and serve immediately with steamed rice and other savoury protein dishes.
Notes
Fermented tofu (aka fermented bean curd, tofu cheese) comes in different sizes and saltiness. Adjust the quantity accordingly. The white version is traditionally used for the recipe. You may replace it with the red version but you may need to reduce the quantity as I find it saltier in most cases.