Start by preheating a large pot over low-medium heat. Once hot, add the oil, onion and carrots. Cook, stirring occasionally, for 8-10 minutes, or until the onions are translucent. If it starts to stick reduce the heat.
2 teaspoons oil, 1 medium onion, 200 grams (1 ½ cups) carrots
Add the garlic and rosemary and cook for another couple of minutes.
Stir in the potatoes, then add the broth, salt, pepper, and beans. Cover and increase the heat to bring the soup to a boil, then reduce the heat to simmer, covered, for 20-25 minutes. The potatoes should be fork tender when ready. Use an immersion blender to roughly blend the soup, mixing until it reaches your desired texture.
200 grams (1 cup) potatoes, 500 ml (2 cups) vegetable broth, 1 teaspoon sea salt, 1 teaspoon black pepper, 400 grams (2 cups) white beans
Turn off the heat and stir in the kale. Cover and leave the soup for a few minutes for the kale to wilt. If you prefer, you can cook it for a few more minutes instead.
100 grams* (4 cups) kale
Stir in the lemon zest and juice, then taste for seasoning, adjusting if needed. Serve hot. Leftovers will keep for up to three days in the refrigerator or three months in the freezer.
Juice of a lemon, Zest of a lemon
Notes
Increase the amount of broth by an extra 200 ml or so (a scant cup) if you like a thinner soup.* 100 grams if weighed without stems (about 180g if weighed with stems).Use frozen kale: give it a few more minutes in the hot soup, also covered, before stirring to combine. Cubes or blocks will take a little longer to thaw and you may want to bring it back up to a simmer for a few minutes if using larger pieces.