Dump in a half a box of baking soda, then a cup of vinegar, lett it bubble up and out, then turn on the hot water for about three minutes. Guaranteed fresh smell!

Then look under the sink for any signs of leaks.

I had the same problem in my new kitchen. I know where the odor is coming from, but I don't know the correct names for the parts. I have regular white cast iron double sinks, but I bet you have the same problem. Okay, here goes.

Sinks have a trap in the middle of the sink that the strainer fits in to. Your trap was probably not sealed properly, so food collects under it and rots. Then, when you turn on the water after the junk under the trap has had a chance to dry, you get the awful smell, right?

The trap is very easy to reset. It unscrews. It is extremely gross junk under there, but you just need to wash it, dry it and reset it with plumbers putty (the man at the hardware store will tell you what to get) and your problem will be solved!

I'll bet that's it!

Sherry

An update: Thank you so much for all your suggestions. I tried the cleaning ideas mentioned above but the smell came back very quickly (within 1/2 hr). So, I thought the problem Sherry was describing was the culprit, as I could see little bits of food go between the sink and ss trap, so I had our GC back to take it apart and seal the trap (or whatever it's called) about two weeks ago. GC said he didn't see food build up. Smell remained bad, so I insisted GC call his plumber, who had done all the rough ins for the island sink (GC did the hook up once the kitchen was installed). Turns out, plumber had installed an extra large trap under the island floor, and since the GC never knew this -- why he didn't know beats me -- he didn't set up the drains properly. GC plumbed the sink with a U-shaped trap in the undersink cabinet, so there were now two traps. Plumber felt that the two traps were causing the water to flow too slowly and to not allow proper venting -- hence creating this stale smell. GC changed the plumbing route under the sink, I javex-ed and also did the vinegar and baking soda trick that the GC member suggested, and the smell is MOSTLY gone. I still do notice it if I place dishes to dry in one of the sinks so that the drain is covered up. I still don't really understand why I still have this smell - but it's pretty faint and I am trying not to obsess. Any further ideas? I don't think I can get the traps off the sinks now to check for further build-up, as they are siliconed in (or puttied in, not sure which).

What a mess!

Rachel