1/3 cup balsamic vinegar (or dry red wine if you have it)
1/3 cup beef broth
2 tbsp mustard
Coat both sides of steaks with pepper. Heat olive oil in skillet over medium-high heat. Cook steaks until done on each side.
Add garlic, stirring until golden brown (feel free to add more olive oil to keep garlic moist, remember if it gets too brown it gets bitter). Add vinegar (or wine) and broth and bring to boil. Remove steaks from skillet, covering to keep warm. With whisk, stir in mustard until well blended.
Serve sauce over steaks with potatoes, veggies and rolls.