Nummun Thai Kitchen is a Thai restaurant at #01-03 Thomson Imperial Court, 200 Upper Thomson Road, in Bishan, Singapore, holding a 4.5 rating on Google. Its Facebook page stands in for a website.
The craft in good Thai cooking is balance rather than sheer heat — lime for sourness, fish sauce for salt, a thread of palm sugar under the chilli — so a tom yum or som tam should taste rounded, not merely fierce. Kitchens will usually tone the spice down unless you ask, so request the proper Thai level if you want a dish as the cook intends. Dishes arrive as they're ready and are meant to be shared with plenty of rice, which is why three or four plates between two people beats one each.
For Bishan locals, a well-rated Thai kitchen on a stretch of Upper Thomson Road better known for its prata houses and cafes makes a handy change of pace.