- 4 large portobello mushrooms (8 to 10 ounces each)
- 2 large garlic cloves (cut into slivers)
- 1 ounce Romano Parmigiano-Reggiano or other firm cheese (cut into slivers)
- 1 sprig fresh rosemary (leaves stripped off the stem, or 2 teaspoons dried rosemary)
- 2 tablespoons pine nuts
- 1/2 cup plus
- 2 tablespoons balsamic vinegar
- 1/2 teaspoon coarse salt
- 1/2 teaspoon black pepper
- 1 1/3 cups extra-virgin olive oil or more as needed
- 12 fresh basil leaves thinly sliced
- 4 slices Taleggio cheese
- 4 Favourite hamburger buns and toppings
Assemble your ingredients.
To make the Pesto: Puree the garlic, basil, pine nuts, and cheese in a food processor, running the machine in short bursts. With the machine running, work in the lemon juice and olive oil, add salt and pepper to taste.
Trim the stems off the Portobellos. Wipe clean with a damp paper towel. Using a small knife or a skewer, make a series of holes in the gill-side of the mushroom caps, about 1/2 an inch apart. Insert garlic slivers in some of the holes, Romano cheese slivers in some, basil in some, and pine nuts in the remaining holes.
Spread some of the pesto sauce on the bottom of a platter or baking dish. Arrange the mushroom caps on it, and swish them around to coat the bottoms evenly. Spoon the remaining marinade over the Portobellos. Let them marinate, covered, for as little as 30 minutes or as long as 3 hours.
Set up the grill for direct grilling, keeping one zone cool, and preheat to high. When ready to cook, remove the mushroom caps from the marinade and wipe off any excess. Arrange the mushroom caps on the hot grate, gill-side down, and grill for 3 minutes.
Then turn the caps over and continue grilling until the caps are browned and very tender, 4 to 6 minutes, rotating after 2 minutes to create grill marks.
Divide the Taleggio cheese among the caps (the gill-side should be up) and move to the cooler side of the grill until the cheese melts.
Serve at once using your favourite burger buns and toppings. Savour the yummy fungal flavours.