Grilling portobello mushrooms is not a challenging task in and of itself, but simple steps like marinating the mushrooms, flipping them as they cook, and taking careful account of all stuffing components before beginning will make the process smoother — and may result in a more flavorful dish, as well. There are various techniques that chefs often employ when grilling gourmet mushrooms like portobello. Which tips and tricks are best depends to some extent on personal preference, but basic guidelines on heat, moisture, and cook time are good places to start.
Like most types of mushrooms, the portobello is tender and porous, with a moist flesh that is sensitive to heat. Grilling portobello mushrooms requires a careful attention to cook time and flame height so as to prevent the fungi from drying out or losing texture. Simply sitting a mushroom on the grill bed is not usually the best approach. This can char the outside while leaving the inside basically uncooked. Uneven cooking can make for an unpleasant taste, and blackening often detracts from the many health benefits of portobello mushrooms.
A gas or propane grill often provides the most control when grilling portobello mushrooms, as flame height is easy to set. Many grillers prefer the smoky flavor imparted by a charcoal grill, though this often requires a bit more attention to heat and cook speed. Cooks usually also flip the mushrooms at least once during grilling to ensure that the heat is evenly distributed to all surfaces. This is a good time to check on the fungi's progress, and make adjustments to the grill settings as necessary.
For many cooks, the easiest way to prevent mushrooms from overcooking or losing their tenderness is to prepare them with a marinade. This can be as simple as rubbing their surface with oil just before grilling, or as complex as soaking the mushrooms overnight in a savory sauce. Portobello mushrooms absorb moisture and flavor, which means that they will soak in oils, juices, and water from their surroundings. A very moist mushroom often grills more evenly, and tastes more tender on completion.
Cooks usually choose marinade flavors that will enhance the flavors of the completed meal. Sometimes, the grilled wholes are used as hamburger substitutes, or are chopped and used in pastas or salads. Other times, the grilled caps are set aside to be stuffed. Matching the marinade to the preparation will make for complimentary flavors.
Grilling portobello mushrooms that have been stuffed is possible, but challenging. It is usually easier to grill the caps first, and prepare the stuffing separately. Grilling portobello mushrooms that have been stuffed while raw is harder, both in terms of ensuring even cooking and keeping the caps looking presentable. Cooks commonly return stuffed portobello caps to the grill for re-warming, however, particularly if the stuffing contains cheese that needs melting. Wrapping them in foil is a good way to help them keep their contents, while also preventing too much heat contact.