Put the onions, tomatoes, carrots, red pepper, chilli, garlic and spices in a large heavy based saucepan with 1/2 to 1 cup of stock.
Cover and bring to boil and boil for 3-5 minutes. Stir in the potatoes and simmer for 3-4 minutes more until liquid has nearly gone.
Stir in remaining stock, simmer partially covered until the potatoes are almost tender, about 5 minutes. Stir in the corn, season with salt and pepper and simmer until all the veg are tender.
3. Take out 1 cupful and liquidise it. Return it to the pot. Mix together the milk and milk powder and add it to the soup. Simmer for another few minutes and adjust the seasoning.
Serve garnished with the fresh chopped coriander and mint.