The Portobello mushroom is a large, mature variety of the Agaricus bisporus species, which also includes the common button mushroom and cremini mushroom. Known for its meaty texture and rich flavor, it is often used as a meat substitute in various dishes, making it popular among vegetarians and vegans. Portobello mushrooms are typically brown and can grow up to six inches in diameter. They are versatile in cooking and can be grilled, roasted, or stuffed. Additionally, they are a good source of nutrients, including vitamins B and D, as well as minerals like selenium and potassium.