Heat 1 tablespoon olive oil in a medium pot over medium-high heat. Add the onion, celery and 1 1/2 teaspoons salt and cook until the vegetables are golden brown, about 5 minutes. Add the beans and broth, bring to a simmer and cook 15 minutes.
Meanwhile, heat the remaining 3 tablespoons olive oil in a large skillet over medium heat. Add the roasted peppers, minced garlic and cilantro and cook until the garlic is soft, about 2 minutes. Stir in the chard, cover and cook until wilted, 1 to 2 minutes. Scrape the contents of the skillet into the pot and simmer until heated through, about 5 minutes. Season with salt and pepper.
Toast the bread, then rub with the whole garlic clove. Serve the soup with the bread and lemon wedges, if desired.