Sort through beans and discard any broken ones or stones. Rinse beans, place in a bowl and add water to cover by 3"; soak overnight. In a dutch oven over medium-high heat, warm olive oil. Add lamb shanks a few at a time and brown on all sides, 10 to 12 minutes. Add garlic and cook, stirring, 1 to 2 minutes. Drain beans, rinse and add to pot along with wine, broth, tomatoes, tomato paste, thyme and bay leaf; stir to mix. Add lamb shanks, bring to a simmer, and reduce heat to low. Cover and simmer until beans are tender and meat is nearly falling off the bone, 3 to 4 hours. Season with salt and pepper; remove and discard bay leaf. Transfer lamb shanks and beans to individual plates; garnish with lemon zest and parsley, Serve immediately.