1Place the escarole in a large, nonreactive bowl and set aside. Heat the oil in a large frying pan over high heat. When the oil smokes, add the mushrooms, garlic, shallot, and thyme and season generously with salt and pepper. Cook, stirring occasionally, until the mushrooms are browned and tender, about 5 to 6 minutes.
2Remove the pan from heat and transfer the mushrooms to the bowl with the escarole. Pour the vinegar into the pan. Stir, scraping up any browned bits from the bottom of the pan, then pour over the salad. Toss all the ingredients together, season with additional salt and pepper, and serve.