Prepare the parsley properly: Wash and completely dry the parsley. Finely chop it by hand. Avoid over-processing to maintain texture.
Mince the garlic: Finely mince garlic so it distributes evenly throughout the sauce. Crushing it slightly before chopping helps release flavor.
Combine dry ingredients first: In a bowl, mix parsley, garlic, oregano, chili flakes, salt, and pepper. Stir to distribute evenly.
Add vinegar gradually: Pour in red wine vinegar and mix. Let it sit for 1–2 minutes to soften garlic intensity.
Add olive oil slowly: Drizzle in olive oil while stirring continuously until the sauce becomes loose but not watery.
Taste and adjust: Adjust salt, vinegar, or chili depending on balance. It should taste bright, slightly sharp, and lightly spicy.
Rest before serving: Let the chimichurri sit for at least 20–30 minutes so flavors blend properly.