1. Divide spring mix among 4 serving plates; set aside.
2. Heat oil in a large non-stick skillet over medium-high heat. Add a single layer of mushrooms and cook, without stirring, for about 5 minutes or until mushrooms become red-brown on one side. Turn the mushrooms and stir in shallot or onion, red pepper and garlic. Cook for 5 minutes or until shallot or onions begin to soften.
3. Remove from heat and transfer to a separate bowl. Stir in vinegar, sugar, salt and pepper and mix until sugar is dissolved. Spoon mushroom mixture on top of greens and scatter fresh chives on top. Serve immediately.
Recipe and photos courtesy of the Mushroom Council and mushroominfo.com