Finely chop the garlic and onion.
Roughly chop the vegetables and set aside.
Heat the oil in a large pot and gently sauté the onion for 5 minutes, then add the garlic and cook for another 3 minutes or so. Add the chopped vegetables, except the tomatoes, then the herbs and stir for a couple of minutes.
Add the tomatoes and enough water to cover the veggies. Add the stock cubes and bring to the boil.
Cover and cook for 20 minutes.
Using a stick blender, process the soup until it’s smooth, then add the cavolo nero and kidney beans and bring back to the boil. Cook for 5 minutes and serve.