Lemony White Bean Soup

Name: Lemony White Bean Soup
Ingredients: 1 medium onion, coarsely chopped; 2 celery stalks, coarsely chopped; 1 lemon, zest removed in wide strips, lemon halved; 6 garlic cloves, coarsely chopped; 3 Tbsp. extra-virgin olive oil, plus more for drizzling; Freshly ground black pepper; 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt, plus more; 8 oz. dried white beans (such as cannellini), soaked overnight, drained; 1 quart low-sodium vegetable broth; 2 Tbsp. unsalted butter; Finely chopped parsley and toasted sourdough bread (for serving)