The festival takes place in the beautiful tree-filled downtown city park. Dozens of vendors sell olive oils, canned olives, tapenades and vinegars. Many of these are flavored.
Thus Pasolivo offers lemon, orange and tangerine-flavored olive oils. Others vendors offer flavored olives. Every year, I also buy flavored vinegars (try the black cherry & fig flavored ones!) Most of the vendors offer free tastes with great crusty French bread for dipping.
And of course, wine tasting is part of the equation. Expect about 15 wineries to pour tastes, though you do have to pay for these. I was told by one winery that they really love this event, since the emphasis of the Festival is on food, people tend to drink moderately.
There are even a few artist and food vendors there as well. Downtown "Paso" is also chock-full of great restaurants (as well as many great boutiques) if you want to enjoy lunch or do even more shopping.
Housekeeping details. Bring cash, since many vendors can handle that more easily than credit card/ATM etc. The day is usually fairly warm, so hats and light clothing are advisable.