Years ago when we were in Chicago for one of our summer vacations, we went on an architectural walking tour with a group of friends, lead by Kathleen who's a docent for the Chicago Architectural Foundation. We ended up near The Bean and had lunch at a busy restaurant catering to tourists... I had a grilled portobello burger. I'm sure the combination of exercise and good friends had a lot to do with it... but that was a *damn* good sandwich. The thought of re-creating it has stuck with me. Then I came across this version from Cook's Country in an ATK email. Of course I made a few tweaks.
4 portobello mushrooms (4 to 5 inches in diameter)
1/4+ c. extra-virgin olive oil
1/4 c. red wine vinegar
3-4 cloves garlic, minced
Salt and pepper
4 ounces feta cheese, crumbled (1 cup)
1/2 cup jarred roasted red peppers, patted dry and chopped
1/2 cup oil-packed sun-dried tomatoes, patted dry and chopped*
4 (1/2-inch-thick) slices red onion
4 kaiser rolls, split & buttered for toasting
1 ounce (1 cup) baby arugula
sriracha mayo
*I've been omitting the peppers and using sun-dried tomatoes NOT packed in oil... in that case, I use 2 oz dried tomatoes and add a little olive oil because the filling seems a bit dry. (Probably not needed if you use the roasted peppers.)
Scrape gills out of mushrooms using a spoon (grapefruit spoons work even better if you have them). Using tip of paring knife, cut 1/2-inch crosshatch pattern on tops of mushroom caps, 1/16 inch deep. Combine oil, vinegar, garlic, 1 teaspoon salt, and 1/2 teaspoon pepper in 1-gallon zipper-lock bag. Add mushrooms, seal bag, turn to coat, and let sit for at least 30 minutes or up to 1 hour.
Combine feta, red peppers, and sun-dried tomatoes in bowl. Whisk mayonnaise and basil together in separate bowl (I used straight mayo). Push 1 toothpick horizontally through each onion slice to keep rings intact while grilling (this is GENIUS!).
FOR A CHARCOAL GRILL: Open bottom vent completely. Light large chimney starter filled with charcoal briquettes (6 quarts). When top coals are partially covered with ash, pour evenly over grill. Set cooking grate in place, cover, and open lid vent completely. Heat grill until hot, about 5 minutes.
...OR...
FOR A GAS GRILL: Turn all burners to high, cover, and heat grill until hot, about 15 minutes. Turn all burners to medium-high.
Clean and oil cooking grate. Remove mushrooms from marinade, reserving excess. Brush onions all over with reserved mushroom marinade. Place onions and mushrooms, gill side up, on grill. Cook (covered if using gas) until mushrooms have released their liquid and are charred on first side, 4 to 6 minutes. Flip mushrooms and onions and continue to cook (covered if using gas) until mushrooms are charred on second side, 3 to 5 minutes. Transfer onions to platter; remove toothpicks. Transfer mushrooms to platter, gill side up, and divide feta mixture evenly among caps, packing down with hand. Return mushrooms to grill, feta side up, and cook, covered, until heated through, about 3 minutes. . Return mushrooms to platter and tent with aluminum foil. Grill rolls cut sides down until lightly charred, about 1 minute. Spread basil-mayonnaise on bun bottoms and top each with 1 mushroom and 1 onion slice. Divide arugula evenly among burgers, then cap with bun tops. Serve.
