Herbs: Rinse and dry the parsley and the oregano, and remove the leaves from the stems. Chop the herbs into a fine texture.
Garlic: Remove the skin from the garlic. Chop finely, or I like to use a garlic press.
Serrano Pepper: Remove the seeds from the pepper and finely dice.
In a medium bowl or jar, combine the onion, parsley, oregano, garlic, salt, and red pepper. Add the oil and vinegar and mix well.
Store covered for a couple of days and use before the herbs start to turn brown.
This recipe makes about 2 cups of chimichurri sauce.Food Processor InstructionsAdd all ingredients to the bowl of a food processor. Pulse until ingredients are finely minced.Make AheadYou can make chimichurri sauce up to 4 days ahead.Mix all of the ingredients together in a Mason jar, but then do not add vinegar until the day that you will be serving the chimichurri.