Finely chop the parsley and cilantro, and finely mince the red onion, garlic, and chili pepper.
Add them all to a bowl, along with the olive oil, vinegar, oregano, salt, and pepper.
Mix everything together very well and serve alongside grilled steak, chicken, or other grilled foods.
Optional: Store the sauce in the fridge in an airtight container for 2 hours before serving to let the flavours develop.
Notes
Storage and Make Ahead InstructionsThis chimichurri sauce keeps well in the fridge in an airtight container for up to 3 days. To help preserve it, add a thin layer of olive oil on top. This will help the herbs stay green.