Rinse and soak glutinous rice with turmeric powder and dried tamarind slices for at least 7-8 hours or overnight. Drain rice well and leave aside.
Line the base of a steamer with a piece of banana leaf. Place the rice on the banana leaf and mix in peppercorns. Arrange screwpine leaves over. Steam for 25 minutes over rapid boiling water.
Put rice into a large mixing bowl. Mix salt with coconut milk and pour over the rice. Stir to mix. Place the mixing bowl in the steamer and steam for 10 minutes.
When rice is almost cooked, stir well and continue to steam for another 5 minutes. Remove and leave aside to cool.