I ran across this one after much searching online one afternoon looking for a Rib Marinade. I made a few changes that I'll put in after the original.
1/4 C Olive Oil
1/4 C Worcestershire Sauce
1 1/4 C Soy Sauce
2 TBS Balsamic vinegar
1 TBS Dijon Mustard
4 Cloves Garlic
That's it. I didn't have Balsamic Vinegar or Dijon mustard so tried it with both white and cider vinegar and regular mustard, it seemed fine. I also added some sweetner to it. First time some maple syrup along with regular mustard, white vinegar on ribs and it was great. Second time for chicken I used molasses, cider vinegar and a little Old Bay Seasoning for spice. Also great. Leaving out the Old Bay and using either brown or horseradish mustard would be interesting. I also let it sit for a few hours turning occasionally. One other thing. I used garlic powder not the cloves and since I love garlic just dumped in what looked good to me.
Both really made the meat tender. I suspect the vinegar helped break down the meat fibers while the olive oil moistened it up. Cooked over low-med on the grill and the ribs/chicken were very juicy.
Great basic and easy marinade with stuff you have in the cupboard. Wife liked it enough that she wrote it down as " Jon's All Time Best Marinade"