I find this is a very effective home remedy for sore throat, cough and cold. I have tried a few times and it's proven effective.
A 900gm bottle of I think more than 50 pieces of preserved calamansi (kit cai) stuffed with preserved plum cost only RM28.00, it is a product of Tenom, a town in Sabah, popular with its tangerine and coffee, yes, Yit Foh and Fatt Choi brands coffee are both from Tenom.
Back to the Asam Boi, I usually served it warm to treat the sore throats problem for my daughters, take the drinks 2-3 times a day. The preserved calamansi is very tasty too. It is also very refreshing serving it cold on a hot day.