With a batch of homemade vegetable broth in the fridge, this delicious and nutritious soup is so quick to prepare that it is a definite candidate for a weekday dinner. You can swap other greens, like spinach or kale, for the chard. This soup tastes even better after being chilled for a day or two.
Per serving:
Heat oil in large saucepan over medium heat. Add onion, fennel, and salt; heat, stirring frequently, until vegetables are softened and beginning to brown, about 10 minutes. Add garlic and chili flakes; heat for 1 minute. Add tomatoes and juice from can; bring to a boil and maintain a strong boil for 5 minutes. Add beans, broth, and vinegar; simmer gently for 15 minutes. Stir in chard and cook until wilted.
Ladle soup into serving bowls and garnish with fennel fronds and freshly ground black pepper.