In Argentina they serve this with almost every beef dish. It compliments the dish without overpowering it.

1 bunch of Italian flat leaf parsley roughly chopped.
1/4 cup extra virgin olive oil.
1 lemon juiced.
4 or 5 cloves of garlic minced.
1 tsp each kosher salt, fresh ground black pepper, crushed red pepper.

Place parsley, garlic, in a medium sized bowl. in a separate bowl, whisk olive oil and lemon juice together untill it turns golden. Pour over parsley and garlic. Add salt and pepper and crushed red pepper.
Let the flavors blend for about ten minutes before serving. Spoon some over your beef and enjoy.