This quick and easy ong choy (water spinach) recipe has only 4 ingredients but is loaded with tons of flavor. The secret ingredient is fermented bean curd which gives this vegetable stir-fry a unique taste.

My family always has a jar of fermented bean curd on hand. We typically eat it as a side dish with porridge or as a base for dipping sauces. Did you know it also makes a great stir-fry sauce? It works well with most leafy greens, but to me, the perfect complement is ong choy (water spinach). This easy ong choy recipe has only 4 ingredients yet it's packed with flavor and loaded with nutrients.
What is Ong Choy, Rau Muong or Water Spinach?
Ong choy is a leafy green vegetable recognized by it's long hollow stems and long slender leaves. It's known by many names. Ong choy in Cantonese and Kong Xin Cai (空 心菜) in Mandarin are the terms we use the most at home. In Vietnamese, it's called rau muong. In English, it's known as Chinese water spinach or swamp spinach, named for its growing medium. Despite its English name, it's actually not a spinach but part of the morning glory family. Although, it does have a similar flavor profile to spinach with a natural sweetness. The leaves are tender and the hollow stems are crisp and complement each other so well. It's one of my favorite vegetables.
How to Prepare Ong Choy
Ong choy often comes in a large bunch. It can be a little difficult to manage because of its size. Keep the bundle of ong choy together and trim about 2-4 inches off the stem, discarding the bottom portion. Although the entire stem is edible, the thicker bottom portion tends to be a bit fibrous and less tender.
With the remaining bundle, cut it into more manageable sections about 2-3 inches long. Then give it a good wash. The leaves and stems catch quite a bit of dirt and grit so be sure to wash it well before cooking.
How to Make Fermented Bean Curd Sauce for Ong Choy
There are several different types of fermented bean curd such as red, white, traditional and spicy. They all have a similar salty, cheesy, umami-rich quality. It's this flavor profile that makes fermented bean curd such a unique ingredient. The little tofu cubes come in glass jars and can be found in most Asian grocery stores. For this recipe, you can use any type or brand you like or whatever you already have at home.
Preparing the fermented bean curd sauce is super easy. In fact, the trickiest part is getting the first cube of tofu out without breaking it. A pair of chopsticks and a little finesse is all you need. Luckily for this recipe, you won’t need to worry too much about breaking it since we'll be mashing it up anyway.
Place a cube of fermented bean curd in a small bowl with a spoonful of the liquid from the jar. If the brand you're using contains whole soy beans, include a few of those as well. Add a teaspoon of sugar and mash up the fermented bean curd until you have a coarse paste. Add a bit more liquid from the jar if it's too dry. The consistency should be a little runny with tiny chunks of fermented bean curd.
One important note about using fermented bean curd is that you always want to use clean utensils whenever you dig into the jar. If your utensils have touched other food or has been in your mouth, do not stick it back into the jar. You want to avoid introducing contaminants into the jar, which will cause it to mold quickly. I always dedicate a pair of chopsticks for the bean curd. If the chopsticks have touched anything else, use a clean pair if you need to get more out of the jar.
If you're a fan of ong choy like I am, be sure to check out our other recipe for Stir Fried Ong Choy with Sacha Sauce.
Ingredients
- 1 lb ong choy (water spinach)
- 1 tablespoon cooking oil
- 3 cloves of garlic, minced
- 1 cube fermented bean curd with liquid, mashed
- 1 teaspoon sugar
Instructions
- In a small bowl, mix together 1 teaspoon of sugar with 1 cube of fermented bean curd, plus 1 teaspoon of the liquid from the jar. Mix until it reaches a slightly runny and chunky consistency. Add more liquid if necessary.
- Heat a wok or skillet over high heat. When it begins to get smoky, add 1 tablespoon of oil and swirl the oil around to coat the pan.
- Turn down the heat to medium and stir fry the garlic until it begins to change color, about 10-20 seconds.
- Add the ong choy and turn the heat back to high. Toss constantly until the ong choy begins to wilt, about 20-30 seconds.
- Pour in the fermented bean curd sauce and continue tossing until the sauce is well incorporated and the ong choy is fully cooked. It's ready when the leaves are tender and the stems are crisp.
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