When using a non-stick pan, I find that sometimes you still need to add a little oil to keep the food from sticking. When cooking vegetables eg. onion and garlic, sprinkle a little salt in the pan before adding the vegetables. The salt helps bring the moisture out of the vegetables as they cook thus preventing sticking as well as the need to add oil. Using this trick, you can add vegetables that are not high in moisture content eg. coarsely chopped carrot without adding oil.