Cauliflower indian soup

I found this recipe in the book Le migliori ricette dall'India, I tried it and it was delicious!

Ingredients:

1 big potato

1 small cauliflower

1 onion

1 teaspoon of oil

1 clove of garlic

1 tablespoon of fresh chopped ginger

2 teaspoons of turmeric powder

1 teaspoon of cumin seeds

1 teaspoon of mustard

2 teaspoons of coriander powder

1 l of vegetable soup

300 ml of yoghurt

salt

pepper

Cut the potato in cubes, the cauliflower and onion and put it in a big pan with oil and 3 spoons of water. Cook it on low heat for 10 minutes. Add garlic, ginger and the rest of the spices. Mix well and cook it for a few minutes. Add soup, salt and pepper. When it boils cook it for 20 minutes on low heat, then blend it and at the end add yoghurt. You can garnish with some chopped fresh coriander (but you'll never eat this in my home) or parsley.