Recipe from: Sam and Katie's Favorite Recipes, 1992
1 cup bottled Italian dressing
1/2 cup low-sodium soy sauce
3 Tbsp Worchesteshire sauce
2 tsp. hot Chile oil
1/4 cup dark brown sugar
2 to 4 tsp balsamic or red wine vinegar
Whisk all ingredients together. Add beef, coat and marinate in refrigerator, the longer the better (up to 3 days).
Another variation is to delete the worchesteshire sauce and add fajita seasoning to taste.