I am not usually fond of the Indian-Muslim style of mee siam with thicker gravy but to my surprise, I rather enjoyed the one from "Warong Anika Rasa Muslim Food". This is a stall inside the food court on the second level of the IRAS building.
I think it's due to their tasty gravy striking an ideal balance with the fresh lime and sweetish sambal. Plus their beehoon had been pre-fried so it was already quite shiok. I really like that they threw on plenty of chives too.