NOTE: If using dried beans, follow steps 1 and 2. Can also use canned beans.
If using dried beans versus canned, you will need to soak them. Wash beans; sort through for small rocks and dirt. Place them in separate bowls, and add enough cold water to cover them by at least 1 inch. Soak 4–6 hours.
Cook beans in three medium pots. Fill pots with water, and bring to a boil. Drain beans, discard soaking water, and add them to boiling water. Boil over high heat for 10–15 minutes. Lower heat to a gentle simmer, partially cover the pots, and cook beans until tender but firm, 30–60 minutes. Check beans occasionally; if the water starts to get low, add hot water from a teakettle. Add ½ teaspoon salt to each pot close to the end of cooking. Drain beans, and let cool.
In a small jar or glass container, mix together lemon juice, lemon zest, garlic, oil and remaining ½ teaspoon salt. Close lid tightly, and shake jar until ingredients are well blended.
In a medium serving dish, mix together beans, carrots, celery, bell pepper and onion. Add vinaigrette, and gently toss ingredients. Sprinkle with parsley. Add salt if needed and ground black pepper to taste.