Water spinach (Ipomoea aquatica) is a semiaquatic, tropical plant grown as a vegetable for its tender shoots and leaves. It is found throughout the tropical and subtropical regions of the world, although it is not known where it originated.
This plant is known in English also as river spinach, water morning glory, water convolvulus, or by the more ambiguous names Chinese spinach, Chinese Watercress, Chinese convolvulus, swamp cabbage or kangkong in Southeast Asia. Occasionally, it has also been mistakenly called “kale” in English, although kale is a strain of mustard belonging to the species Brassica oleracea and is completely unrelated to water spinach, which is a species of morning glory. It is known as phak bung in Thai, ong choy in Cantonese, kongxincai in Mandarin Chinese, rau mung in Vietnamese, kangkong in Tagalog, trokuon in Khmer, kolmou xak in Assamese, kalmi shak in Bengali, kangkung in Indonesian, Malay and Sinhalese and hayoyo in Ghana.
Water spinach is most commonly grown in East, South and Southeast Asia. It flourishes naturally in waterways and requires little, if any, care. It is used extensively in Burmese, Thai, Lao, Cambodian, Malay, Vietnamese, Filipino, and Chinese cuisine, especially in rural or kampung (village) areas. The vegetable is also extremely popular in Taiwan, where it grows well. During the Japanese occupation of Singapore in World War II, the vegetable grew remarkably easily in many areas, and became a popular wartime crop. In the Philippines, a variety of kangkong is grown in canals dug during the American occupation after the Spanish–American War, while another variety growing on land is called Chinese kangkong.
The vegetable is a common ingredient in Southeast Asian dishes.
- In Singapore, Indonesia, and Malaysia, the tender shoots along with the leaves are usually stir-fried with chilli pepper, garlic, ginger, dried shrimp paste (belacan/terasi) and other spices. In Penang and Ipoh, it is cooked with cuttlefish and a sweet and spicy sauce. Also known as eng cai in the Hokkien dialect, it can also be boiled with preserved cuttlefish, then rinsed and mixed with spicy rojak paste to become jiu hu eng cai. Boiled eng cai also can be served with fermented krill noodle belacan bee hoon and prawn noodle.
- In Indonesian cuisine it is called kangkung, boiled or blanched together with other vegetables it forms the ingredient of gado-gado or pecel salads in peanut sauce. Some recipes that use kangkung is plecing kangkung from Lombok, and mie kangkung (kangkong noodle) from Jakarta.
- In Thailand, where it is called phak bung (Thai: ผักบุ้ง), it is eaten raw, often along with green papaya salad or nam phrik, in stir-fries and in curries such as kaeng som.
- In Vietnam, I. aquatica (rau muống) is a common ingredient and garnish in Vietnamese cuisine and was once served as a staple vegetable of the poor. In the South, the water spinach is julienned into thin strips and eaten with many kinds of noodles. It is also commonly cooked in a sour soup (canh chua), with tomatoes, other vegetables, and some kind of protein. Rau muống is also commonly sauteed with chopped garlic, oil (or pork fat), and fish sauce, known as rau muống xào tỏi (stir-fried water spinach with garlic) and served as a side dish in many meals.
- In Laos, where it is known as pak bong (ຜັກບົ້ງ), and in Burma, where it is called gazun ywet , it is frequently stir-fried with oyster sauce or yellow soybean paste, and garlic and chillies.
- In the cuisine of Cambodia, where it is called trakuon (Khmer: ត្រកួន), water spinach is known to have a few types. The popular type is the usual local water plant, used in many traditional dishes. One type is known as Chinese trakuon grown as a straight stalk plant from soil. This type is known to be used in stir fry with pork or just with marinated soy beans (sieng). The Khmer popular dish samlar machu (sour soup) uses water spinach with fish or chicken. Water spinach is also eaten raw or parboiled along with other vegetables in dip dishes, e.g. toeuk kroeung, a sour/salty taste dish, with roughly minced fish mixed with lemon juice, crushed peanuts, basil, and prahok (fish paste) flavour, similar to nam phrik.
- In the Philippines, where it is called kangkóng, the tender shoots are cut into segments and cooked, together with the leaves, in fish and meat stews, such as sinigang. The vegetable may also be eaten alone, such as in adobong kangkóng, where it is sautéed in cooking oil, onions, garlic, vinegar, soy sauce, and bouillon cube. A local appetiser called crispy kangkóng has the leaves coated in a flour-based batter and fried until crisp, similar to Japanese vegetable tempura.
- Chinese cuisine (Chinese: 空心菜; pinyin: kōngxīncài; literally: “hollow vegetable”) has numerous ways of preparation, but a simple and quick stir-fry, either plain or with minced garlic, is probably the most common. In Cantonese, the water spinach is known as 通菜 (Jyutping: tung1 coi3) or 蕹菜 (Jyutping: ung3 coi3, sometimes transliterated as ong choy). In Cantonese cuisine, a popular variation adds fermented bean curd. In Hakka cuisine, yellow bean paste is added, sometimes along with fried shallots.
- In South India, the leaves are finely chopped and mixed with grated coconut to prepare thoran (തോരന്), a dish in Kerala. The same dish in Tamil Nadu is prepared as thuvaiyal (துவையல்) or as kootu (கூட்டு).
- In Bangladesh and West Bengal, it is known as kolmishak (কলমীশাক) and stir-fried preparation of the leaves is a very popular dish.
Preparation and Cooking
Kang kong has a mild, not bitter flavour. The leaves are harvested before the plants flower to preserve the fresh, sweet taste. In Vietnam the green is eaten raw in salad or added to soup. In other parts of Asia the greens are lightly cooked with a savoury or spicy paste made with chillies. The stems take a bit longer to cook so they should be added first then the leaves only take a few seconds to heat and wilt.