The main gist of the article is here:
Helena Echlin of CHOW's column Table Manners gives some advice on how to politely take photos of food in restaurants, especially upscale restaurants. It may sound obvious, but doesn't hurt to hear again: Don't use flash, don't move around the table too much, and don't take so many photos that the dish's temperature drastically changes by the time you get to eat it. I see the "no flash" rule broken the most when I eat out; use the highest ISO setting on your camera, use some sort of stabilizer, put a candle in front of your food—or perhaps that dish just isn't meant to be photographed since using flash will make it look bad anyway.
I totally agree with Helena. I never use flash in restaurants and I try not to move around too much. I also turn my ISO up as high as I can. I can get it up to about 1600 ISO and then I'll use Lightzone to reduce the pixelated look to it. And I always shoot in RAW so I can fix up pictures later. Most restaurants have lighting that'll give an yellow hue to your pictures. iPhoto has a program that will change the white balance. I always shoot in Aperture priority. It's the AS setting on the camera. TV is shutter speed and it's for taking pictures of things that are in motion. The other thing you can do is that you can just change the white balance setting on your camera. You can do this by moving the cursor over to the little thing that looks like a lightbulb. If you are under florescent lights, then move the cursor over to that one.
Now my main point about taking pictures in restaurants is that you should be poised and collected. Have a sense of presence and don't be shy about taking pictures. This is why 9 out of 10 times the pictures don't come out right. If you are going to take a picture then take the picture. If someone has a problem with it, then what's the worse they can do? Are they going to kick you out? I don't think so. Sure you might get the odd looks every once in a while, but how often have you seen people taking pictures of themselves in cafes with their cellphones? Staring at them isn't going to change them from doing it.
Be assertive and know how to take the best picture in the optimal amount of time because you don't want to disturb the people at your own table. They want to eat the food while it is hot. So... It's all about preparation. Set your camera to the optimal setting before the food gets there. Take a sample picture of your table setting so you get an idea of how your pictures will come out. After your settings are set then save them some how or simply let your camera sit. It won't kill your battery.
As long as you are assertive, then nobody cares if you are going to take a picture. Plus, everyone will ask you for the pictures.