Turmeric gives a lot of flavor and a nice yellow color to vegetable soups. Miso paste also works as a great soup base, miso has fat but you don't need to use very much.
I like to buy turmeric and other spices at Indian markets. I use the dried ground turmeric, but they also have fresh turmeric, which is supposed to be extremely healthy.
Asian supermarkets have a good selection of miso varieties, I've been getting Japanese miso made without bonito (fish flakes), since I don't like to eat anything that comes from our polluted oceans or waterways.