How to tell a friend his cooking sucks?

[david k]

A week ago, my friend invite me over for dinner, and his cooking sucks. It sucked so much that when he's not looking, I would hide the food in napkin and excuse myself to the bathroom and flush the food away. Not only that, he touches the food while cooking. For example: Just the other time, I spotted him touching the food while making soup; He puts beef and carrots in the soup, and while cooking he would stick his thumb and index finger in the pot, and pinch the beef and put it in his mouth then he would repeat that about 3 times. I'm like what the hell are you doing man, and he's like don't worry I'm clean. I am the type of person who gets disgusted when somebody touches my food even if you have clean hands. While eating, I kinda threw up in my mouth a little, and it just very uncomfortable. He's planning to invite me over again, and I don't know what to say. I used to think it's easy to tell a person that their not good, but it's harder than you think. A food that normally takes 1 hour to cook, he would finish in less than 15 minutes. How can I tell him politely without offending him?