Heat a large skillet over high heat. Add oil; swirl to coat. Sprinkle steaks evenly with 1/4 teaspoon salt and 1/4 teaspoon pepper. Add the steaks to the pan; cook 4 minutes on each side or until desired degree of doneness. Remove steaks from the pan. Let stand for 5 minutes.
Reduced the heat to medium-high. Add the shallots and thyme to the pan; saute 1 minute or until lightly browned. Add the wine; cook 2 1/2 minutes or until the liquid almost evaporates. Add the stock; cook 3 minutes or until the liquid is reduced by half and the mixture is slightly thickened. Remove the pan from heat. Add the remaining 1/8 teaspoon salt and 1/8 teaspoon pepper, butter, and mustard; stir with a whisk.
Cut the steak across the grain into thin slices; serve with the sauce. Sprinkle with chopped parsley.