Steam sweet potatoes and yam separately for 10?15 minutes or until soft. Set aside. Boil soaked black-eyed beans until soft. Drain and set aside.
Put sago in a sieve then place sieve in a large bowl. Rinse sago under running tap water then cook the sago in a pot of hot water until transparent. Remove and rinse under cold water and drain. Add colouring to sago and coat with 2 tablespoons tapioca flour.
Squeeze and strain grated coconut to obtain thick coconut milk. Add salt to the thick coconut milk and keep refrigerated. Add 1.2l water to the coconut residue and squeeze to obtain thin coconut milk.
Boil sugar, water and pandan leaves until sugar dissolves. Add thin coconut milk and continue to boil for 5?6 minutes. Add yam, sweet potatoes, black-eyed beans and sago. Stir evenly. Add thick coconut milk and at the first sign of boiling, immediately remove the pot from the heat. Remove the pandan leaves and serve either hot or cold.