Hi Nancy, this marinade is for flank steak, the amounts are approximate but it is absolutely delicious. It comes from my daughter Elizabeth who is a wonderful cook, and we usually marinate for at least 2 days.
Marg in Ontario Canada

Flank Steak

Approx 1/4 cup balsamic vinegar
Approx 1/2 cup soya sauce
1/4 tsp sesame oil
hot pepper flakes
fresh chopped cilantro (app 1/2 cup)
garlic powder ( app 1 tsp)
1 ? 2 tsp sugar

Flank Steak
Marinate at least 2-4 hrs but 1-2 days is best
Recipe will be added to the marinade section of Nancy's Kitchen.

http://www.nancyskitchen.com