Wild mushrooms, seared scallops, and portobellos -- large, meaty mushrooms with a strong, earthy flavor -- combine in this light but satisfying meal.
Rinse and dry scallops. Heat oil in a 10-inch nonstick skillet over medium-high heat. Add scallops and sear until golden brown, about 3 to 5 minutes per side. Remove from pan and set aside.
Add portobellos; cook over high heat until they start to soften, about 2 minutes. Add shiitakes, thyme leaves, garlic, and shallots; cook for 2 minutes. Season with salt and pepper and cover. Cook until mushrooms begin to release their juices and are soft, 3 to 5 minutes more.
Add wine and soy sauce, reduce heat to medium low, and cook until liquid is reduced to a glaze.
Return scallops to skillet and toss to coat well with glaze. Adjust seasonings if necessary. Arrange arugula and watercress on 4 plates; spoon scallops and mushrooms over greens and garnish each serving with a sprig of thyme.