In a blender container or food processor bowl, combine the green onions, mayonnaise dressing or salad dressing, vinegar, Dijon-style mustard, garlic, and pepper.
Cover and blend or process until green onions are finely chopped.
Transfer the dressing mixture to a medium bowl. Stir in the yogurt. Makes about 1-1/4 cups salad dressing (twenty 1-tablespoon servings).
Prepare as above. Cover and store in your refrigerator for up to 1 week.