Step 1: In a medium bowl or a jar with a tight-fitting lid, combine the extra virgin olive oil, red wine vinegar, minced garlic, dried oregano, dried basil, dried thyme, onion powder, red pepper flakes (if using), Dijon mustard (if using), salt, and black pepper.
Step 2: If using a bowl, whisk vigorously for 1-2 minutes until all ingredients are well combined and the dressing is emulsified (slightly thickened and opaque). If using a jar, screw on the lid tightly and shake vigorously for 30-60 seconds until emulsified.
Step 3: Taste the homemade Italian dressing and adjust seasonings as needed. You might want more salt, pepper, or a bit more vinegar for extra tang.
Step 4: For best flavor, let the dressing sit for at least 15-30 minutes at room temperature before serving to allow the flavors to meld. This homemade Italian dressing is even better after chilling in the refrigerator for a few hours.
Step 5: If desired, stir in fresh chopped parsley just before serving. Shake or whisk again before each use, as the oil and vinegar may separate naturally.