1) Put the parsley, cilantro and garlic into a medium mixing bowl and toss to combine.

2) Add the vinegar, salt, red and black pepper and stir.

3) Pour in the olive oil and mix well to combine. Allow the mixture to sit for 30 minutes to allow the flavors to blend. This sauce is not only great on steak but I think it would also be wonderful on pork and chicken as well.