In a medium bowl, combine the chopped cilantro, minced garlic, and finely chopped red onion.
Add the red wine vinegar, lime juice, salt, and red pepper flakes to the bowl and mix well.
Gradually pour in the olive oil while stirring continuously to blend all the ingredients together.
Allow the chimichurri to sit for at least 10 minutes before serving to let the flavors meld together. For best results, let it sit for an hour or more.