A portobello is a large, meaty mushroom with a flat, brown cap that can grow as wide as your hand. These mushrooms have a rich, earthy flavor and a dense texture that makes them popular as a vegetarian alternative to burgers or steaks. When you bite into a grilled portobello, it feels substantial and satisfying in a way that smaller mushrooms don't.

Portobellos are actually just mature cremini mushrooms (the brown mushrooms you often see at the grocery store). Left to grow longer, cremini mushrooms open up into the large, flat caps we call portobellos. The gills underneath the cap darken to a deep brown or black as the mushroom matures.

These mushrooms became especially popular in the 1980s and 1990s when creative cooks discovered how well they worked on the grill. You can stuff them with cheese and breadcrumbs, marinate and grill them like a steak, or slice them into pasta dishes. Because they're so large and sturdy, portobellos hold up well to cooking methods that would turn smaller mushrooms mushy. Many restaurants now serve portobello burgers as a hearty vegetarian option that even meat-eaters enjoy.