Chimichurri is a very basic uncooked sauce and it does not (and should not) taste particularly good on its own. It is used to enhance the flavor of meat, so I would not try to read much from how it tastes alone.
- 1 cup water
- 1 tbsp coarse salt
- 1 head garlic, separated into cloves and peeled
- 1 cup packed fresh flat-leaf parsley leaves
- 1 cup fresh oregano leaves (Origanum vulgare)
- 2 tsp crushed red- pepper flakes
- 1/4 cup red-wine vinegar
- 1/2 cup extra-virgin olive oil
- Prepare a brine by dissolving the salt in boiling water, let it cool
- Chop the garlic very finely and place it in a medium
- Finely chop the parsley and oregano and add to the garlic together with the red pepper flakes.
- While stirring, add the red wine vinegar, then the olive oil and the brine.
- Transfer to a container with a lid and let it cool in the fridge for a day.
- It is better to prepare it the day before use so the flavors have more time to blend. You can keep chimichurri in the fridge for 2 to 3 weeks.
Source: This is Francis Mallmann's (Well-known Argentinian chef) recipe. This is my own translation from his book in Spanish, but you will find this recipe also in English media such as this one from NYMag
Some more tips:
Do not use balsamic, it will taste completely different. Red wine vinegar has less alcohol than some "alcohol free" beers (1% or less), and there are ones without alcohol at all in them. You could also boil it first, but for 1/4 cup, in a sauce... you couldn't even measure it.
Use dried red pepper in fine flakes, not fresh peppers. If the flakes you can get are from very spicy peppers, just use less. It is not a spicy sauce.
A note on fresh herbs
As unpopular as this might be, the truth is that chimichurri is traditionally made with dried oregano, not fresh. I personally think it's ok to use fresh oregano and the Mallmann thinks so too, but he does make the disclaimer in his book about fresh herbs being "his own take on it".
Parsley, garlic and oregano are the common denominator across both Argentina and Uruguay, but some regions also have variations. As an Argentinian I might be biased. That said, and not being a purist myself: I have never ever found cilantro or capers in Argentinian chimichurri.