Melt the butter in a large pot set over medium heat. Add the next seven ingredients and cook until the onions are translucent, about 5 to 6 minutes. Add the stock, bring to a simmer, and simmer 15 minutes. Add the beans, corn, asparagus and chard or spinach and simmer until the asparagus is bright green and tender, about 4 to 5 minutes. Season with salt and pepper and serve.
Options: If you like the taste of beef stock, use it to make this soup instead of chicken or vegetable stock.You can also add a cup or two of cooked and cubed beef, chicken, or turkey to the soup after adding the stock. Instead of white kidney beans, use another type of legume in this soup, such as chickpeas or black beans.