Cook the mushrooms: Heat a large skillet over high heat. Add mushrooms, lower heat to medium high and cook for 8 to 10 minutes, stirring occasionally. As the mushrooms cook, they will release moisture. Meanwhile, mix the tamari, sesame oil, miso paste, and minced garlic in a small bowl. Once the moisture has burned off, add the tamari mixture and black pepper. Saut茅 until mushrooms have reabsorbed the liquid and have turned a golden brown.
While the mushrooms are browning, prep the remaining vegetables, defrost the edamame, warm the brown rice on the stovetop or in the microwave, and prepare the dressing.
Assemble: Starting with a bed of lettuce, divide ingredients equally between 4 wide shallow bowls or storage containers.
Add optional toppings if desired, then drizzle with dressing./li>