Add steak to a zip top bag and pour in 1/4 cup of balsamic vinaigrette. Remove as much air as possible from the bag and seal. Coat the steak well with balsamic vinaigrette. Chill in the refrigerator overnight or throughout the day (about 8 hours) to marinate.
Remove the steak from the marinade and discard the zip top bag and the leftover marinade. Cook the steak on the grill or as a skillet steak to desired doneness. Use an internal temperature probe to check for you preferred level of doneness. Rare (120º F – 130º F), Medium Rare (130º F – 140º F), Medium (140º F – 150º F), Medium Well (150º F – 160º F).
Remove the steak and allow it to rest as you prepare the remainder of the steak salad.
Arrange the salad greens, tomatoes, cheese and red onion on a large platter or in a large salad serving bowl. Slice the steak into 1/4-inch slices and arrange on the salad. Top with fresh basil and serve with balsamic vinaigrette dressing.