Gently wipe caps clean with a damp towel. If the gills are very dark and you want a milder flavor, use a spoon to lightly scrape them out. Pat dry so the marinade sticks.

Whisk olive oil, balsamic, soy, Dijon, maple, garlic, smoked paprika, black pepper, and a pinch of salt in a shallow dish.

Add mushrooms gill-side up.Spoon marinade over the caps, ensuring they're coated. Let sit 15–30 minutes, flipping once. Longer isn't better here—mushrooms are sponges and can get waterlogged.

Preheat a grill or grill pan to medium-high.Alternatively, use a cast-iron skillet. Lightly oil grates/pan to prevent sticking.

Cook mushrooms 4–5 minutes per side, pressing gently with a spatula for even contact. Brush with extra marinade as they cook.They should darken, soften, and release some juices.

During the last minute, place a slice of cheese on each cap. Cover grill/pan to melt.

Split and toast your whole-wheat buns until golden. A little crunch equals structural integrity.

Spread the bottom buns with umami aioli.Add a swipe to the top buns for good measure.

Layer lettuce, mushroom cap, tomato, avocado, onion, and pickles. Cap it. Press lightly so everything snuggles into place.

Hot, juicy, and slightly messy is the goal.Grab napkins. Maybe two.