Chop the onions. Rinse the spinach, drain. Peel and dice the potatoes.
In a large saucepan fry the cumin seeds without oil. When fragrant, remove them to a plate.
In the same saucepan heat the oil and sauté the onions until soft - about 5 minutes.
Add the garlic, stir through then add the potatoes. Stir for a minute, then pour in the vegetable stock. Add most of the toasted caraway seeds.
When the potatoes are soft, add the spinach and simmer, under cover, for about 5 minutes.
Blend to a smooth, creamy consistency. Stir in some sour cream or yogurt, if you like.
Serve with crumbled blue cheese and the remaining caraway seeds scattered on top.