Whisk together vinegar, brown sugar, shallots, chili paste, garlic, 1 teaspoon oil, and 1/4 teaspoon salt.
Dunk the steak in the mixture and turn to coat. Take steaks out of sauce and reserve liquid. Pat dry the steaks and sprinkle the with rest of the salt.
Pour the rest of the oil in a frying pan and heat over high heat. Place steaks in pan, being sure not to crowd. Cook 4 minutes per side or until desired degree of doneness. Move steaks to a platter and keep in a warm place.
Pour the saved liquid into the pan and let boil over medium-high heat, stirring often until thick, about 3 minutes. Serve sauce over steaks.