Straight from the Earth

PORTABELLA MUSHROOM BURGERS

Who doesn’t love burgers? Portabella mushroom burgers, to be exact. This recipe takes the portabella to perfection: a thick, juicy mushroom, sandwiched between a whole-grain bun along with sweet grilled onion, fresh tomato, crunchy romaine lettuce, and a spicy avocado spread. I like to cook mine in a cast-iron skillet on the stovetop, but they are also delicious cooked on the grill. Sometimes, when I’m feeling decadent, I’ll make double portabella mushroom burgers by stacking two mushrooms for each burger. It’s best to plan ahead; the more time the mushrooms and onion get to marinate, the better. If you would prefer to skip a step and avoid grilling the onion, simply serve thin slices of raw red onion—my dad even likes it better this way. Assemble the burger ingredients right before you’re ready to eat, for the best presentation. Served with mustard, ketchup, and our Baked Sweet Potato Fries with Creamy Ranch Dip (page 173), dinner is bound to be an epic burger experience. Messiness is expected—so keep plenty of napkins on hand. —MAREA

Serves 4

MARINADE

¹/₃ cup/80 ml balsamic vinegar

¹/₃ cup/80 ml extra-virgin olive oil

1¹/₂ tsp minced garlic

1¹/₂ tsp agave nectar

¹/₂ tsp salt

¹/₂ tsp freshly ground black pepper

¹/₄ tsp red pepper flakes

4 portabella mushrooms, slightly larger than the buns, stemmed

1 large red onion, sliced crosswise into four ¹/₄- to ¹/₂-in/6- to 12-mm rounds

3 to 5 tbsp high-heat oil, such as safflower, plus more as needed

4 whole-grain hamburger buns

SPICY AVOCADO SPREAD

1 ripe avocado

¹/₄ tsp salt

¹/₈ tsp red pepper flakes

Ketchup for garnishing (optional)

Mustard for garnishing (optional)

1 large heirloom tomato, sliced crosswise into 4 thick rounds

4 large romaine lettuce leaves, cut in half widthwise

To make the marinade: Whisk together the vinegar, olive oil, garlic, agave, salt, pepper, and red pepper flakes in a small bowl.

Using a sharp knife, make three small slits in the top of each mushroom. Transfer the mushrooms and the onion slices to a rimmed baking sheet and douse them with the marinade. Use a pastry brush to make sure each piece is thoroughly coated, especially the soft undersides of the mushrooms. If the onion rounds come apart, gently place them back together. Allow the onions to marinate for at least 30 minutes, and the mushrooms for at least 1 hour.

Heat a very large skillet, preferably cast iron, over medium-high heat, and film it with a thin layer of high-heat oil. Cook the onion and marinade until the onion is golden brown and caramelized, about 5 minutes. Then flip the slices over very gently (I use two spatulas), and continue cooking for another 5 minutes to brown the other side. It may be necessary to do this in batches, adding more oil to the pan as needed. Don’t worry if the onion falls apart; it will taste delicious anyway. Transfer the onion to a paper towel to drain, and set aside at room temperature.

Position a rack in the middle of the oven and preheat it to 350°F/180°C/gas 4.

Using the same skillet, coat the pan with a thin layer of high-heat oil, and place it over medium heat. Cook the mushrooms until they are tender, 5 to 8 minutes on each side. It may be necessary to do this in batches, adding more oil to the pan as needed.

Split the buns and place them on a baking sheet. Toast them in the oven until they are warm and slightly browned, 5 to 10 minutes.

Meanwhile, make the spread: Combine the avocado, salt, and red pepper flakes in a small bowl and mash with a fork or spoon. Set aside at room temperature.

Smear 2 tbsp avocado spread on the top and bottom halves of each bun. Add ketchup and mustard, if using. Place one mushroom on the bottom half of each roll. Top with a slice of onion, a slice of tomato, and two pieces of lettuce. Cover with the top half of each bun. Indulge immediately.