On the weekend of the 13th/14th of September in Asti there is the Festival Delle Sagre, where the big Campo del Palio (the square that hosts the traditional horse racing event - this year on the 21st of September) hosts stalls from about 50 local towns, where you can sample the food and wine of the region. On Sunday there is also a parade with floats representing traditional farm themes. The official website is in Italian!, but it can give you an idea of what to expect.
Also, in Asti there is the Douja d'Or wine festival from the 12th to the 21st of September, where you can sample around 400 local wines (you can also buy them!). Some information in English can be found on the world events guide.