How to Make It
In a large saucepan, cover the beans with 3 inches of water and bring to a boil. Simmer, stirring occasionally, until the beans are tender, about 45 minutes. Drain.
In a large enameled cast-iron casserole, heat the olive oil. Add the garlic and shallots and cook over moderate heat, stirring, until fragrant and golden, about 3 minutes. Add the beans and tomatoes and season with salt and pepper. Cook, stirring occasionally, until the tomatoes soften, about 3 minutes. Stir in the wine and cook until almost evaporated, about 1 minute. Add the broth and cockles and bring to a simmer. Cover and cook over low heat until the cockles open, about 3 minutes. Stir in the parsley and tarragon and serve with grilled bread.