As an extension of avoidance, sometimes you can neutralize sulfites before eating them.
Hydrogen peroxide is a strong oxidant and widely available as a 3% solution. When added to sulfite, hydrogen peroxide will oxidize the sulfite ions, converting them to the safe sulfate form. Most sulfite problems do not extend to sulfates. If you suspect that a food may be contaminated with surface sulfites, soak it for a few minutes in a sink full of water with a tablespoon of hydrogen peroxide. Then rinse with fresh water before eating. This will convert surface sulfites to sulfates and lower your risk. Of course, if the sulfite has penetrated the interior of the food, soaking won't help very much. You could use this technique on berries (or fish) to improve your odds. Note that a few unlucky people are also intolerant of sulfates. For these people, washing with hydrogen peroxide won't help. Sulfate sensitive people usually react to soap, shampoo and toothpaste containing sodium lauryl sulfate (SLS) causing skin rashes. So if you don't get skin rashes from soap, don't worry about sulfates. (SOURCE)
Chlorella algae, spinach, and wheatgrass have also been studied and proven to neutralize sulfites at various levels of efficacy. Chlorella algae is so named because it contains the highest concentration of chlorophyll for any plant on Earth. As far as sulfites are concerned, what's important is the high concentration of chlorphyll and associated chloroplasts (SOURCE). In the mid-90's Jolivet and coworkers reported that chloroplasts from plants (such as spinach and wheatgrass) contain an enzyme system capable of carrying out the efficient oxidation of sulfite to sulfate.
Lin and Georgiou, proposed methods of sulfite neutralization that include sulfite oxidation kits with chloroplasts and buffer components that could be manufactured by encapsulating chloroplasts in semi-permeable pouches (which could then be put into sulfite beverages). Williams studied the efficacy of sulfite reduction by wheatgrass (reduced by 900 ug) and chlorella tablets (reduced by 1000 ug). (SOURCE)
Jolivet P, Bergeron E, Zimierski A, Meunier J-C. 1995. Metabolism of elemental sulfur and oxidation of sulfite by wheat and spinach chloroplasts. Phytochem 38:9-14.
Georgiou, G, Lin S. 2001. A biocatalyst for the Removal of Sulfite from Alcoholic Beverages. Published online 11 November 2004 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/bit.20307