Combine all ingredients in a large food processor or blender. Pulse until a pesto-like thick sauce forms. Scrape sides as needed to fully mix all ingredients.
Store leftovers in airtight container in the refrigerator. Will last several days without browning.
To make potatoes:
Preheat oven to 400 degrees F. Line baking sheet with parchment paper.
Add potatoes to baking sheet and top with olive oil, salt, and pepper. Toss ingredients to fully coat.
Bake in preheated oven, turning occasionally, until crispy on the outside and soft in the middle, about 25-30 minutes. To serve, top with Chimichurri sauce.