Beef with Tangy Grapefruit Chimichurri Sauce

1. Place garlic, parsley, cilantro, oregano, red pepper flakes, coarse salt and pepper in bowl of food processor; cover and pulse to finely chop mixture. Add grapefruit juice and oil in small stream while food processor is running; process until sauce is smooth. Let sauce stand at room temperature for at least 1 hour before serving.

2. Meanwhile, season flank steak with salt and pepper to taste; grill over medium heat to desired doneness. Remove from heat; let steak rest 10 minutes. Slice flank steak diagonally across grain; place on serving platter and spoon Tangy Grapefruit Chimichurri Sauce on top.