Place roughly chopped red chillis and garlic in a mini-food processor, add the red wine vinegar, and blitz for a few seconds.
Using a silicone spatula, scrape down the side walls of the chopping bowl so that the ingredients are all at the bottom.
Add the olive oil, sea salt flakes, and black pepper, and blitz again for 10-20 seconds. Scrape down ingredients back to the bottom again.
Trim and discard the tips of the parsley and coriander stalks, the roughly chop the stalks and blitz for 20-30 seconds.
Scrape the ingredients once more to the bottom, then add the parsley leaves, blitz for a few seconds, followed by the coriander leaves.
Blitz once more time, then pour out into an airtight container.
Notes
There are numerous variations to Chimichurri sauce, many using fresh oregano (for example). Feel free to experiment with herb combinations.Chillis, as you know, can vary significantly in heat. Having made Chimichurri sauce several times, the overall heat can vary quite significantly. Add as much chilli as you are comfortable with, or if not up for a fiery inferno, you could consider deseeding one of the chillis to tone it down.This keeps well in a fridge for a week or so (but very rare it does not get eaten a lot quicker than that).