Thoroughly wash parsley and oregano, then dry completely using paper towels or a salad spinner. Remove thick stems from parsley, reserving leaves and tender upper stems. Strip oregano leaves from stems.
On a large cutting board, hand-chop parsley and oregano to medium-fine consistency (approximately 1-2mm pieces). Transfer to a medium mixing bowl.
Add minced garlic, red pepper flakes, salt, and black pepper to the herbs. Stir to distribute evenly.
Pour in red wine vinegar and stir for 30 seconds, allowing acids to begin breaking down cell walls. Slowly drizzle in olive oil while whisking continuously to create a partial emulsion.
Cover bowl and allow sauce to rest at room temperature for a minimum of 30 minutes (optimal: 60 minutes) for flavor compounds to integrate.
Before serving, taste and adjust salt, acid, or heat levels as needed. The flavor should be vibrant with balanced acidity.