Finely chop the onion and garlic.
Peel and dice the kohlrabi.
Cut the broccoli into chunks, using both florets and stems.
Heat the olive oil in a large pot over medium heat.
Add the onion and sauté for about 5 minutes, until softened.
Stir in the garlic, caraway seeds and marjoram (or oregano), and cook for 1 minute until fragrant.
Add the kohlrabi and broccoli to the pot, stirring to coat with the aromatics.
Pour in the stock and bring to a boil.
Reduce the heat to low, cover, and cook for 15–20 minutes, until the vegetables are tender.
Add the parsley leaves and blend the soup with a stick blender until silky smooth.
Stir in the white beans (if using) and gently reheat.
Add the apple cider vinegar and season with salt and pepper to taste.
Serve warm with sourdough bread, quinoa, or your favourite grain.