Slice tops off mushrooms, you can keep these to use later for another recipe. Then cut each in pieces about 1 - 1 1/2 inches thick, to resemble scallops. Place mushrooms in a 9x9 baking dish, or another dish or container of a similar size. One that will fit mushrooms, without leaving too much excess room in the dish (see photo above).

Whisk together marinade ingredients and pour in dish over mushrooms. Marinade should cover the bottom half of each mushroom piece. These will now sit for 1-2 hours. Half way through marinating, flip each mushroom so both ends get saturated.

Melt margarine in a large skillet over medium heat. Once margarine is melted, add garlic. Sauté for 1-2 minutes.

Add 1/2 cup white wine plus the red onion. Sauté on medium heat until onion slices are translucent. While onions are cooking you may also add the lemon, salt, and pepper.

Place mushrooms (but not the marinade) in skillet and let cook 5 minutes. Keep broth at a simmer. If it starts to boil, turn down the heat a bit. Flip the mushrooms and add the chopped whites of scallions. Cook for an additional 5 minutes, adding dill after 4 minutes.

Check for doneness by putting pressure on the tops of the mushrooms, to see if they've gotten soft. Some may need a minute or two more. Move these to the hottest part of your skillet. To serve, place one serving of brown rice on a deep plate or in a bowl. Align "scallops" around the rice. Spoon broth over scallops and top with the chopped greens of scallions. Garnish with dill if desired.