By Kenzo TRIBOUILLARD / AFP In Belgium, a country reputed for its beer, mushrooms nourished on a byproduct from the brew are doing booming business. In Belgium, a country reputed for its beer, mushrooms nourished on a byproduct from the brew are doing booming business. The high-end fungi grown by a Brussels firm, Eclo, in a disused abattoir are finding their way to gourmet customers — while boosting the circular economy. The seven mushroom varieties produced by Eclo are mostly sought-after exotic types usually found in Asia, including shiitake, maitake (also known as hen-of-the-woods) and pom…