Place the steak in a baking pan just large enough to hold it and pierce all over with a fork.
In a small bowl, combine the soy sauce, brown sugar, lemon juice, mustard, ginger, garlic, sesame oil, pepper, and half the sherry; pour over the steak.
Cover and refrigerate overnight, turning the steak once.
Remove the steak from the marinade, pat dry and score crisscross fashion.
Lightly coat a heavy 10 inch skillet with the cooking spray and set over moderate heat about 30 seconds.
Cook the steak 3 minutes on each side for rare, 2 to 3 minutes longer for medium rare or medium.
Transfer to a warm platter.
Cool the skillet for 1 minute.
Meanwhile, to prepare the glaze, combine the remaining sherry with the vinegar, water, and granulated sugar in a small bowl; add to the skillet and cook, stirring, over moderate heat until thickened 1 to 2 minutes.
Spoon the glaze over the steak, then slice the meat on the bias 1/2 inch thick.