The following is a Chimichurri recipe I got from ex-con Martha Stewart (recipe source is the owner of a Argentinean restaurant in Norwalk, CT):
2/3 cup chopped flat-leaf parsley
1/3 cup chopped garlic
1/2 cup vegetable oil
1/4 cup apple cider vinegar
1 teaspoon coarse salt
1 teaspoon black pepper
1 teaspoon cayenne pepper
3 tablespoons paprika
1 tablespoon dried oregano
1 1/2 tablespoons balsamic vinegar
Combine all ingredients in a jar and shake until well combined.
As another poster suggested, I like to add some cilantro to this recipe.