portabello, portabella, portobella
The word portobello originated as a way to help glamorize and sell mature cremini mushrooms (which were also given a snazzy Italian-sounding name to boost sales). But if all of this sounds more like Marketing 101 than cooking, know this: creminis have more flavor than white mushrooms, and portobellos have more flavor still.
The portobello was “discovered,” probably by accident, when cremini caps were left to grow, open up, and develop gills. Creminis take about seven weeks to grow to the size at which they’re picked. Those that are not picked then mature to become portobellos within three to five days, often growing to six inches across in size. During this growth spurt, the mushroom’s gills become fully exposed, causing it to lose moisture. The loss of moisture concentrates the mushroom’s flavor and gives it the dense, meaty texture for which it’s renowned.
Choose firm, plump portobellos with a pleasant, earthy smell. Avoid any that appear limp or dried out. The mushrooms should not be shriveled or slippery, which suggests decomposition.
Though you can eat portobellos raw, cooking them makes them tender and intensifies their flavor. These large mushrooms take especially well to searing, grilling, roasting, and braising.
Perhaps the best way to understand a portobello’s greatness is to try one grilled. To start, remove the stem, wipe the cap, brush it with olive oil, and sprinkle both sides generously with coarse salt. Grill over a hot fire for a few minutes on each side. While you’d never mistake a mushroom for meat, the smoky, earthy flavor of a grilled portobello gratifies in the same way.
Portobellos also take well to roasting. While other mushrooms shrivel away to almost nothing when roasted, portobellos start out so big that they finish with a good amount of mushroom left, even when cut into pieces.
Braising portobellos is a great way to boost their flavor. As the mushrooms cook, they absorb the braising liquid. Their sponge-like nature also makes them good candidates for marinades.
Though most people are concerned only with the meaty caps, you can use all parts of a portobello. The stems, once trimmed and wiped cleaned, can be chopped up to use in a duxelles as you would use the stems of cultivated mushrooms. The gills, however, will turn anything you cook dark grayish brown, so it's best to scrape them off. You can also scrape out the gills to make a little more room if you're stuffing the mushrooms. But if you don't want to waste the gills, add these flavorful scrapings to stocks or dark sauces.
Once you get portobellos home, remove any wrapping, spread them on a tray, cover them with paper towels, and place the tray in an area of the refrigerator that allows air to circulate. The mushrooms should keep this way for about a week.
Cooked portobellos, in tightly sealed freezer bags or containers, can be frozen and will keep for several months. Uncooked mushrooms don't freeze well.