Shiitake mushrooms are one of the few nonanimal sources of of vitamin B12, according to Professor Mo Mei Chen of the University of California, Berkeley. Shiitakes are also low in calories and rich in other vitamins and minerals including copper, iron, magnesium and potassium. Substitutes for this Japanese mushroom include portobello, oyster and porcini mushrooms.
Portobello mushrooms are recommended as a substitute for shiitake, according to the Gourmet Sleuth website. Also called a "brown crimini mushroom in disguise" by Gourmet Sleuth, portobello mushrooms can be utilized not only as a shiitake substitute, but they are often used as a meat substitute. Fresh portobello mushrooms should be plump and firm with an earthy smell and should never appear slippery or shriveled. Portobellos can be grilled, roasted or sauteed. Use portobellos in recipes for wild mushroom sauce, salads that call for mushrooms and walnut and mushroom pate. Brown crimini mushrooms, which are small portobellos, can also be used as a shiitake substitute, according to The Cook's Thesaurus.
Oyster mushrooms can be used when shiitakes are not available, Oyster mushrooms grow on trees and are identified by their scallop-like caps and snow-gray or tan color. They often appear on dead hardwood trees and blue, yellow, pink and white capped oyster mushrooms are also available. King oysters are the largest type of this mushroom and have a mild hint of abalone. Oyster mushrooms are often used in stir fry dishes because their thin caps cook quickly, according to the Mycological Society of San Francisco. Add oyster mushrooms last in dishes that take a long time to prepare to avoid burning them. Stems should be discarded before use and the gills should be thoroughly rinsed because insects often hide in them, says the San Francisco Mycological Society.
Porcinis are brown-capped mushrooms that are standard in European cuisine and have a robust, nutty flavor. Porcinis have round, fleshy caps that are often soft and smooth, and they have long, fleshy stalks. Unlike other types of mushrooms, the underside of the porcini cap is covered in tube-like, vertical pores instead of gills. They can be used as a substitute for shiitake mushrooms, and they can be used in pasta and risotto recipes. You can also use porcinis as a meat substitute for burgers. Remove the poricini stems and vertical tubes before cooking them.