Guaranteed Winner London Broil - cooking recipe

Ingredients

3 -5 lbs london broil beef
1/4 cup oil
1/3 cup vinegar
2 onions, diced (or chopped)
6 garlic cloves, minced
3 tablespoons tamari (soy sauce)
3 tablespoons brown sugar
1/2 teaspoon pepper

Preparation

Combine everything except the meat in a large plastic bag. Add the meat and close well. Marinate overnight, or at least for a few hours.
Roast meat, covered, for 30 minutes per pound of meat at 400F, or until meat is tender.
I often let it cool, cut it, and reheat it, but it is delicious any way.
In the original recipe they recommend broiling the meat for 5 to 10 minutes per side before roasting, but I must admit that I have never bothered to do so and it is still delicious each time.