Preheat oven to 350 degrees. Reserve the seasoning packet from the bag of bean soup and soak the beans overnight in warm water or for at least 4 hours. Rinse and drain.
Heat 1 tablespoon of olive oil in a Dutch oven (or other oven proof large pan with a lid) over medium high heat. Add the leeks and cook until soft, about 8 minutes. Add the garlic and cook for 30 seconds. Add the wine to the hot pan and cook stirring until almost all the wine has evaporated, about 1 minute. Add the mustard and stir to combine. Add the chicken stock, beans and seasoning packet. Stir to combine. Cover the pan and put in oven for 1 hour and 15 minutes.
After you put the beans in the oven, season the chicken thighs well with salt and pepper. Heat a large skillet over medium-high heat and add 2 tablespoons of olive oil. Brown the chicken thighs 5 minutes per side. Place on a plate and refrigerate until ready to finish cooking. After 1 hour and 15 minutes, add the chopped tomatoes and browned chicken thighs to the beans and continue to cook for 1 more hour. Remove beans and chicken from the oven, add the lemon juice. Taste the beans and add more salt and pepper is desired. Combine the grated lemon zest with the minced parsley and sprinkle on top of the dish. Serve the dish with an extra drizzle of olive oil if desired.