Wonderful little find on Upper Thomson Road, along the same row of shophouse coffeeshops as the 24h Roti Prata House (with the crispy prata).
It's called Hwa Nam Chinese Restaurant (华南菜馆) and it serves excellent freshly-steamed dim sum at $2 per plate. Fantastic! With incredibly friendly and affable staff, you can also order roast duck and other Cantonese cooked dishes from the kitchen.
Do check it out. Closed on Mondays.