Bring 3 quarts of water to boil in a dutch oven or large saucepan. Stir in farro and 1 tablespoon salt. Return to boil, reduce heat. Simmer, uncovered, until tender, 15 to 20 minutes. Drain well and set aside.
Heat oil in a 12-inch skillet over medium-high heat. Add mushrooms, onion, thyme, and 1/4 teaspoon salt; cook, stirring frequently until moisture has evaporated and vegetables start to brown, 5 to 8 minutes.
Add sherry and cook, scraping up any browned bits, until pan is almost dry, 1 to 2 minutes. Add farro and cook, stirring constantly until heated through, about 1 minute. Remove pan from heat, stir in parsley, white wine vinegar, and season with salt and pepper to taste.
Notes
Sometimes I add a couple cloves of minced garlic after the onion and mushrooms begin to brown.
This recipe was calculated using the exact brands and measurements I used to make this recipe. If you are following a strict diet please note changing anything will cause the nutritional info to change. My calculations are intended as a guide only.