Green Bean and Tuna Salad with Basil Dressing

Name: Green Bean and Tuna Salad with Basil Dressing
Ingredients: 1 shallot, coarsely chopped; 3 Tbsp. sherry vinegar or red wine vinegar; 1 tsp. kosher salt, plus more; 1 lb. green beans, trimmed; 1 1/2 cups basil leaves; 6 Tbsp. extra-virgin olive oil; 2 Tbsp. fresh lemon juice; 1 tsp. freshly ground black pepper; 1 large or 2 small heads of Little Gem lettuce or romaine hearts, leaves separated; 1 (14.5-oz.) can white beans, drained, rinsed; 1 cup parsley leaves with tender stems; 1/4 cup capers, drained; 1 (6-oz.) jar oil-packed tuna, drained, flaked into pieces