Cut off and discard ends of orange.
Coarsely chop orange, discarding any seeds if necessary.
Transfer orange, herbs, vinegar, miso, mustard, garlic, ginger, salt, and pepper to a food processor or blender, and process until very finely chopped, about 1 minute, stopping to scrape down sides of bowl halfway through.
With processor or blender running, gradually pour oil through food chute until smooth and creamy, about 30 seconds.
Season with additional salt to taste.
