If you go to Siem Reap, Jasmine is recommended -- a small restaurant with a roof and no walls, just surrounding flowers. Everything was great.
Probably the best known, most widely consumed dish is fish amok, which is fish combined with coconut milk, chile paste, and eggs and steamed into something that, depending on the cook, ranges from custard to thick soup. Great stuff. The fish may not be anything you've heard of, but will likely come from Tonle Sap, the largest lake in SE Asia. Tonle Sap is another thing worth visiting, as well, if you do get to Siem Reap -- cold water, so whole communities live in boats on the water, as it's cooler than living on land. There are whole towns -- a Cambodian town, Vietnamese, Chinese, etc. -- and schools, stores, everything is on the water. You can tour by boat. It's quite wonderful.)
Cambodian food is influenced by Thailand, but also by the French, and you often see people on bicycles with loaves of French bread in their baskets.
Lots of fish, lots of coconut, easier on the heat than Thailand or Laos, all great. Oh -- and chopsticks (as is the case in most of Southeast Asia) are for noodles. You use a fork and spoon for other food.
Have a great time. I loved Cambodia, and long to return. The people were absolutely wonderful.
However, you might want to stop at REI and get a cooling scarf (don't remember the brand name, but they'll know what it is) -- it's a neck scarf filled with tiny bids that absorb and hold water, but let the cloth dry out. It stays cool and can lower your body temperature by as much as 10 degrees -- which can make a big difference in Cambodia, which can be mighty toasty.