Portobello Mushrooms Recipe

Clean and slice mushrooms

Wipe each portobello clean with a damp paper towel to remove dirt. Remove stems if present. Slice mushrooms by hand into 1/4-inch thick slices (about 8–10 slices per mushroom depending on size). Pat slices dry with paper towels to remove excess moisture.

Marinate quickly

In a medium bowl combine 1 tablespoon olive oil, 1 tablespoon soy sauce, 1 teaspoon lemon juice and the thyme. Toss the sliced mushrooms gently to coat and let sit 5–10 minutes while you prepare the batter. This adds flavor and helps retain some moisture.

Make the batter

In a medium bowl whisk together 1 cup all-purpose flour, 1/4 cup cornstarch, 1/2 teaspoon baking powder, 1/2 teaspoon garlic powder, 1/2 teaspoon smoked paprika, 1 teaspoon kosher salt and 1/2 teaspoon black pepper. In a separate small bowl beat 1 egg. Slowly whisk the beaten egg and 1 cup cold sparkling water into the dry ingredients until just combined — the batter should be slightly thick but still pourable; small lumps are fine. Keep batter chilled if possible (place bowl in an ice bath) until ready to use.

Optional panko coating

If you want extra crunch, place 3/4 cup panko breadcrumbs in a shallow dish. After dipping battered mushroom slices, press them lightly into panko to coat before frying. If you prefer only battered (tempura-style), skip this step.

Heat the oil

Pour 2 cups neutral oil into a large heavy skillet (or use a deep fryer) to a depth of about 1/2 to 3/4 inch. Heat over medium-high heat until oil reaches 350°F (175°C) or until a small drop of batter sizzles and browns within 20–30 seconds. Maintain temperature between 325–350°F while frying.

Fry mushrooms

Working in batches (do not overcrowd), pat marinade off the mushroom slices briefly, dip each slice into the batter to coat completely, then optionally press into panko. Carefully place slices into the hot oil and fry 2–3 minutes per side until golden brown and crisp. Use tongs or a slotted spatula to flip. Adjust heat as needed so the exterior browns without burning and mushrooms cook through.

Drain and season

Transfer fried mushrooms to a wire rack set over a baking sheet or to paper towels to drain. Immediately sprinkle with the additional 1/2 teaspoon kosher salt while still hot. Keep warm in a low oven (200°F / 95°C) if frying multiple batches.

In a small bowl combine 1/2 cup mayonnaise, 2 teaspoons Dijon mustard, 1 teaspoon lemon juice, 1/2 teaspoon minced garlic, 1/2 teaspoon honey (or maple), 1/4 teaspoon salt and 1/4 teaspoon black pepper. Whisk until smooth. If the aioli is too thick, whisk in 1 teaspoon olive oil or up to 1 tablespoon water to reach desired consistency. Taste and adjust seasoning—add more mustard for tang or honey for sweetness. Chill until ready to serve.

Arrange the fried portobello slices on a platter. Sprinkle with chopped fresh parsley and serve with lemon wedges and the Dijon aioli on the side for dipping. Recommend serving immediately while hot and crisp.

Storage: Leftover fried mushrooms are best reheated in a 400°F (200°C) oven for 8–10 minutes on a wire rack until crisp. Store aioli in an airtight container in the refrigerator for up to 3 days.