Green Goddess Orzo Salad

Name: Green Goddess Orzo Salad
Ingredients: 1 1/4 cups packed fresh watercress (or baby spinach); 3/4 cup packed fresh parsley; 1/4 cup roughly chopped fresh dill; 1/4 cup roughly chopped fresh tarragon; 3 tablespoons roughly chopped fresh chives; 2 teaspoons capers; 1 teaspoon finely grated lemon zest, plus 2 tablespoons fresh juice; 1 small clove garlic; 1/2 small shallot; Pinch of sugar; 4 teaspoons white wine vinegar; 1 1/2 teaspoons Dijon mustard; 3/4 cup mayonnaise; 1/4 cup sour cream; Kosher salt and freshly ground pepper; 8 ounces cooked orzo; 3/4 cup cooked frozen peas; 6 ounces marinated artichoke hearts, preferably grilled, drained and chopped (from a 14.5-ounce jar); 1/2 bunch asparagus (about 8 ounces), trimmed and thinly sliced on the diagonal; 1 1/2 cups sugar snap peas (about 6 ounces), strings removed and thinly sliced on the diagonal; Freshly ground pepper; 1/4 cup roughly torn fresh dill