This salad and all its interesting components get rave reviews!
Heat oil in a large skillet over medium-high heat. Add a single layer of mushrooms and cook, without stirring, for about five minutes or until mushrooms are browned on one side.
Turn the mushrooms and stir in shallots, red pepper, and garlic. Cook for five minutes or until shallots and pepper begin to soften.
Remove from heat and transfer mushroom mixture to a bowl. Stir in vinegar, sugar, salt, and pepper and mix until sugar is dissolved.
Divide salad greens among four serving plates.
Spoon mushroom mixture on top of greens and scatter scallions on top.