Wash the broccoli, celery and zucchini. Divide the broccoli into florets. Peel and dice the stem. Peel the celery bulb and cut into small pieces. Dice the zucchini as well.
Heat the oil in a large saucepan and cook the broccoli and caraway seeds in a closed saucepan for 5 minutes. Meanwhile prepare the vegetable stock. I simply pour boiling water over about 2 teaspoons of vegetable stock powder. Put the vegetable stock with all the remaining ingredients except the lemon juice in the saucepan and cover and simmer for 7-10 minutes.
Puree everything with a hand blender to a creamy consistency. Add lemon juice, stir well and season with salt and pepper if necessary.
Serve warm with pumpkin seeds and possibly a dollop of cream cheese or crème fraîche.