I grew up in Nigeria, where mushrooms weren’t a feature in the kitchen, or at the table. Years later, I’d learn that mushrooms were present, fresh and dried in kitchens across Nigeria, in the southeast, and in the southwest.
The first and second photos are by James Ransom, my friend and photographer who took the photos for Chop Chop.
The first mushroom-adjacent thing I learned about was ósú- an edible mushroom tuber. It is known variously as pleurotus tuber regium which forms a substrate for mushrooms to grow.
When I look up pleurotus tuber regium, I come across a variety of things which look quite different from what I know of ósú, sometimes (erroneously?) called usu. It is likely that there’s a range of possibilities and geometries in the family.
My first thought was “This must be like a truffle” but they aren’t the same thing. Ero ósú, Mushroom ósú or king tuber mushroom, like truffles grow where mushrooms are found during the rainy season. And while ósú, like truffles lack caps or stems, they do not have any flavor per se, or aroma. They are brown-skinned, like Nigerian yams, and are peeled to get at the white interior which is bright, spongy, and without scent or fragrance and makes a good binder with oily seeds.
It is ground down, combined, often with ground egusi seeds and processed. It binds to the egusi with the addition of water, the mix causes the release of a nutty egusi oil, and a firm dough is the result. This is enjoyed cooked as a textural element in soups, but also as a protein-rich meat replacement called #mgbam.
In the southeastern states of Abia, Anambra, and Imo, the cakes of egusi and mgbam are combined with tender hearts of achara, a perennial grass to make ofe achara, a ceremonial version of Ẹ̀gúsí Soup (page 253 of my cookbook).
The soup is commonly served at parties, weddings, New Yam festivals, and other events.
There’s more to learn about ósú and I’ll share as much as I can.
