The chopped sun dried tomatoes make this dressing a little chunky. If you'd prefer a smoother dressing, you can make it this way:
Add the sun dried tomatoes and garlic to the food processor, and pulse until finely chopped. Add the mayonnaise, sour cream, and process until completely smooth (adding a little buttermilk if necessary). Add in the herbs, some of the buttermilk, and lemon, and pulse until the herbs are finely chopped and evenly distributed throughout the dressing. Add more buttermilk as needed to thin to desired consistency, and season to taste with more salt.
Recipe adapted from
THIS RECIPE from Foodie Crush.