Soak beans overnight.
Drain and bring to a boil with chicken stock and add enough water to cover the beans by about 2 inches. Lower heat and simmer uncovered for about 30–45 minutes until al dente (not thoroughly soft).
Sauté onion, carrots and celery until they begin to soften. Add garlic and sauté another minute. Add chard and sauté till it wilts. Add tomato sauce and simmer 15 minutes.
Add partially cooked beans and their cooking liquid and cook 45 minutes to 1 hour until beans are soft.
Season to taste and serve.