Asparagus with Smoked Salmon and Gribiche Sauce

Name: Asparagus with Smoked Salmon and Gribiche Sauce
Ingredients: 1/4 cup mayonnaise; 1/4 cup sour cream; 2 tablespoons fresh lemon juice; 4 hard-boiled eggs, finely chopped; 2 tablespoons drained capers; 2 tablespoons chopped fresh parsley; 1 tablespoon chopped fresh tarragon; 1 tablespoon minced shallot; 24 white and/or green asparagus spears; 1/2 lemon; 1 tablespoon butter; 1 teaspoon sugar; 3 tablespoons extra-virgin olive oil plus additional for drizzling; 8 ounces thinly sliced smoked salmon