1 cup fresh flat-leaf parsley, tightly packed (about 1 bunch of parsley)
1 cup fresh cilantro, tightly packed (about 1 bunch of cilantro)
1/2 cup diced red onion
3 Tablespoons fresh oregano, tightly packed (optional)
3 cloves of garlic, peeled
2 Tablespoons fresh lemon or lime juice
2 Tablespoons red wine vinegar
¼ tsp sea salt
¼ tsp freshly-ground black pepper
¼ tsp red pepper flakes, or more, to taste
½ cup good-quality olive oil
Add all ingredients except the olive oil to a food processor, and pulse a few times until chopped. Slowly stream in the olive oil, while pulsing the mixture a few more times until the olive oil is combined, and stopping to scrape down the sides of the food processor if needed.
Serve immediately, or cover and refrigerate for up to 3 days.