Chop the cilantro, oregano, and garlic with a knife instead of a food processor. Using a knife helps keep the chimichurri chunky and avoids bruising the herbs.
Place all of the ingredients in a bowl and mix well. You can use the mixture immediately, but the flavors really begin to meld if you let the chimichurri rest for about 4 hours.
Keep the chimichurri in a mason jar on the counter for up to a week. Do not put the chimichurri in the refrigerator or the olive oil will coagulate.