On a rimmed baking sheet, toss 1 lb. thinly sliced baby portobello mushrooms with 2 Tbsp. extra-virgin olive oil, 2 tsp. reduced-sodium soy sauce or tamari, and 1/2 tsp smoked paprika. Roast the mushrooms at 425° until golden, about 30 min., adding 1 finely chopped garlic clove for the last 1 min. of cooking. Spread vegan mayonnaise on 1 side of 2 pieces whole-grain toast. Layer sliced tomato, lettuce, and mushrooms on 1 piece of toast; top with the other slice.
Recipe by Laura Rege.