Portobello Swiss Burger Recipe

Prepare mushrooms

Wipe portobello caps clean with a damp cloth and remove stems. If desired, gently scrape gills with a spoon to reduce moisture. Pat dry and set caps aside.

Slice onion

Peel the onion and slice into 1/4-inch rings or half-moons so they cook evenly.

In a small bowl, whisk together smoked paprika, dried thyme, garlic powder, onion powder, salt, and black pepper. Add olive oil and softened butter (if using) and stir to make a loose paste.

Heat a large skillet over medium-high heat until hot. Add 1 tablespoon olive oil if pan is dry. Add the sliced onion and sauté 4–6 minutes, stirring occasionally, until softened and starting to caramelize. Add the minced garlic and cook 30–45 seconds until fragrant.

Push the onions to one side of the skillet. Add the remaining 2 tablespoons of the oil-seasoning mixture to the pan (or spread mushrooms with some of the mixture). Place portobello caps gill-side down and cook 4–5 minutes until they begin to brown. Flip mushrooms, brush or spoon remaining seasoning over exposed surfaces, and cook another 4–5 minutes until tender and cooked through. Reduce heat to medium if mushrooms are browning too quickly. Combine mushrooms with the onions in the skillet for 30 seconds to marry flavors.

Lower heat to low. Place one Swiss cheese slice on each mushroom cap. Cover the skillet with a lid for 1–2 minutes to melt the cheese. If using an oven broiler, transfer mushrooms to a baking sheet and broil 1–2 minutes until cheese is melted and bubbly—watch closely to prevent burning.

While cheese melts, butter the cut sides of the buns and toast them in a separate skillet or on a griddle over medium heat until golden, about 1–2 minutes per side.

Assemble the burgers: spread condiment on bun bottoms, add a handful of arugula or lettuce, place a cheesy portobello cap on top, spoon some of the caramelized onions over the mushroom, add tomato slices if using, and finish with the bun top.

Serve immediately while warm. Optionally serve with fries, salad, or pickles on the side.