"Classic bean soup recipe. Can be made Italian by adding 3 tablespoons pesto and 1 cup cooked pasta to the finished soup. Can be made Mexican by using black beans, adding 1/2 teaspoon red pepper flakes and 2 teaspoons cumin when tomato paste is added. Can be made chunky by adding diced carrot, potato and shredded cabbage to the veggie list."
Pour water over navy beans in a large container to cover by several inches; soak 8 hours to overnight.
Combine soaked beans, chicken broth, water, onion, celery, garlic, and bay leaf in a large pot; bring to a boil. Reduce heat to low and simmer, partially covered, until beans are almost tender, about 1 hour.
Stir tomato paste and sea salt into bean mixture; simmer soup another 45 minutes. Remove and discard bay leaf.
Ladle about half the soup into a large bowl; pour soup into a blender, working in batches, filling blender no more than half full. Hold lid down; pulse a few times before leaving on to blend until smooth. Pour pureed soup into pot with unblended soup; stir in parsley and adjust salt and pepper to taste.