Preheat oven to 450 degrees F. Wash potatoes and pat dry.
In a medium bowl, toss potatoes with 2 tbsp. olive oil and a pinch of salt and pepper.
Spread onto baking sheet and arrange cut-side down. Bake for 30-35 minutes, until golden and crispy.
Meanwhile, make the chimichurri sauce: In a food processor or blender, add vinegar, garlic, cilantro, parsley, oregano, and salt, and mix for about 1 minute, stopping once to scrape down sides. With processor or blender running on low, add olive oil and puree until smooth.
Transfer mixture to serving bowl. If using red pepper flakes, add to bowl and stir to combine.
While still warm, toss potatoes with ⅔ of chimichurri sauce. Reserve ⅓ of sauce to drizzle over potatoes after plated.
Serve potatoes warm. Store leftovers in an airtight container for up to 4 days.