This recipe came from my mom's recipe collection. It is easy to mix up and should be made ahead since it is a marinade and all. It is good on both pork and steak, but Mark will tell you that pork is his top choice for it...
1/3 cup white vinegar
1/3 cup vegetable oil
3 tbsp brown sugar
3 tbsp soy sauce
2 tbsp minced onion
1/8 tsp garlic powder
1/2 tsp black powder
Blend ingredients together. (I actually use a blender to make sure everything blends together well)
Pour marinade over meat (we used boneless pork chops tonight) in a shallow dish or a gallon ziplock bag. Refrigerate. For pork, marinate for 24 hours. For steaks, marinate for at least 12 hours.
When you are ready to grill, remove the meat from the marinade. Discard the remaining marinade.
Edited 4/21/12 Here are some steaks grilling after soaking up this marinade all day. It was yummy. :)