Because, in a nutshell, it is very high in beta carotene, vitamin K, vitamin C, lutein, zeaxanthin, and reasonably rich in calcium. Kale also contains sulforaphane (particularly when chopped or minced), a chemical with potent anti-cancer properties and it is said to help the body in a natural detocification process.
Boiling decreases the level of sulforaphane; however, steaming, microwaving, or stir frying do not result in significant loss. Along with other brassica vegetables (i.e. cabbage), kale is also a source of indole-3-carbinol, a chemical which boosts DNA repair in cells and appears to block the growth of cancer cells, and it is also a good source of carotenoids Wikipedia>.
Those are just some of kale’s health benefits, but what about the flavour and texture? We all know how dreadful spinach can taste…
There is a definite nuttiness to the leaves which remain meaty when steamed, but turn beautifully crisp when stir fired in butter or good quality oil. And that’s exactly how I chose to cook the leaves for the soup; because it would add a different texture to the soup balancing the softness of cabbage and beans already in the soup.
Now, I’m not sure about you, but I’m impartial to serving many a soups with a hunk of good sourdough or rye, and this soup is no different. However, instead of a fresh hunk, I chose to turn my dark rye sourdough into croutons. It always makes soup so much more fun!