I love curry in soup, too. One soup in my rotation includes curry powder and cauliflower, onion, celery as a base (lots of cauliflower). Then I toss in whatever other bits of veg I have on hand...turnips, zucchini, rutabaga, carrots, cabbage or some other form of leafy green.

I use cabbage in soup a lot...good fiber and nutrients with low calories. And it's affordable. I don't eat grains (so no noodles or rice...cruciferious veggies add good bulk to a soup) or much in the way of starchy foods (so no potatoes for me either) so my grocery bill can easily spiral out of control with the massive amounts of produce I eat lol. Cabbage (and cauliflower!) help keep it in check.