Preheat the oven to 425 F. Heat a pot of water to hot, not bubbling. Get a large half-sheet pan and a large bowl.
Cut the potatoes in half, then cut each half into four wedges. Place the wedges in a large bowl and pour over the hot water. Let stand for 10 minutes.
Drain the potatoes, then spread on a kitchen towel and pat dry. Place on the sheet pan, sprinkle with garlic powder, and toss with the avocado oil. Sprinkle with salt and roast for 20 minutes, then flip the potatoes and roast for 20 minutes longer, until browned and crisp.
In a food processor, combine the onion, garlic, parsley, cilantro, oregano, thyme, salt and pepper flakes. Process until finely chopped, stopping to scrape down as needed.
Pour the vinegar in the feed tube of the processor with the machine running, then follow with the olive oil.
Scrape the puree into a bowl for dipping.
Serve the hot potatoes with the chimichurri sauce.