.Though mushrooms are commonly thought to have little nutritional value, many species are high in fiber and provide vitamins such as thiamine, riboflavin, niacin, biotin, cobalamins, ascorbic acid.^ Also, as far as browning such a large amount of mushrooms with a little oil: I used a nonstick pan and only a tiny amount of oil for each batch. mushroom bourguignon | smitten kitchen 17 January 2010 5