Check this website for a quick and inexpensive list of off the shelf pre and probiotics. The article also explains (in English!) what these things do, and why we need them.
A short list of probiotic foods:
Yogurt, buttermilk, kefir, tempeh, miso, kim chi, sauerkraut, other fermented foods.
A short list of prebiotic foods:
Oatmeal, flax, barley, other whole grains, onions, greens, berries, bananas and other fruit, legumes.
In my opinion, raw would be better than cooked or processed, to keep in the natural benefits.