This is the binjai - a fruit that is almost forgotten by most people when foreign imported mangoes took the local market by storm in the 80's.
The binjai is a sourish fruit of the mango family. It is grown wild in most places in the Rejang and the river mouth areas of the Baram and Limbang rivers. The fruit is still occasionally found in Bintulu. Brunei continues to produce this fruit for the local market. Apparently there is still a good market for this fruit in KK.
Recently I found several trees growing in a relative's farm. He claimed that his grandfather was the one who took the seeds from second division where the Skrang River flowed in pristine conditions a long time ago and planted them. So his binjai fruit trees must have been more than 50 years old. He occasionally sells them in the Brunei open air market at Brunei $2.00 each.
This fruit is usually eaten as part of the rice and fish lunch or dinner. My family would eat it as a appetiser (sliced thinly and mixed with a good sambal or rojak sauce).
Interesting many people also call the fruit "buah tusu lanjut" and it generally amuses a lot of men when it is seen and bought in the market or tamu.
According to the Wikipedia the fruit is scientifically called "Mangifera caesia" and is known also as the Malaysian Mango. It is locally called Binjai in the Malay language. It is a species of mango widely cultivated in areas of Malaysia, Indonesia, Singapore, Brunei, Papua New Guinea, and the Philippines. The tree lives in lowlands or gentle slopes on sandy clay soils. It grows up to 30 m (100 ft) tall with a dense crown of round-shaped leaves. The flowers are purple or pink, 0.7 cm long with five sepals. The fruit is a large, edible, elliptical drupe 10-15 cm (4-6 in) long and 6-8 cm (2-3 in) wide. The skin is thin and brown with darker patches, and the flesh is yellow-white, mushy, and strongly odorous with an acid-sweet or sour taste.
The Binjai is believed to originate from the island of Borneo, but is commonly grown elsewhere for its edible fruit. The tree is one of the most common and valuable mango species in western Malaysia, where it is cultivated extensively in orchards. It is also widely grown in Bali, Sumatra, and Borneo. The fruit can be eaten dipped in chili and dark soy sauce. The wood is used for light construction. Binjai is almost always propagated by seed. The tree requires rainfall that is distributed evenly throughout the year.
Why not grow this fruit in your garden before it becomes an endangered species?
Kwan, TY. "Sightings: A Mysterious Tree Bears Fruit". Green Dot Internet Services.
"IUCN Red List - Mangifera caesia". International Union for Conservation of Nature and Natural Resources.
"Anacardiaceae". Royal Botanic Gardens, Kew.