Most traditional teochew restaurants serve cold crabs, e.g. Mong
Hing Teochew Restaurant at KeyPoint - their teochew food is good,
and my family likes to eat there.
There a new Crab Shack at Upp Thomson Road (opposite the Prata shop
at Sin Ming) that serves steamed flower crabs, but I haven't tried.
This shop is interesting bec it looks like a western joint but is
actually situated in an old local kopitiam, right behind the bus
stop. I see a good crowd on weekends.