Cover rice with water. If not using fresh bean sprouts, soak mung dhal in water in a separate bowl. Leave both to soak overnight then wash rice and mung dhal until water runs clear. Mix rice and mung dhal with salt.
Line a bamboo steamer or top of a metal steamer with a tea towel, or greaseproof paper and spread rice and mung dhal over it. Cover with folded sides of tea towel and/or lid. Steam for about 40 minutes, replenishing water, until cooked. If using fresh bean sprouts, add to cooked rice and fluff through with a fork.