1 quart milk
1 pint water
6 peeled potatoes, cut in chunks
2 handfulls of sliced celery
1 medium onion, diced
2 cloves garlic, sliced.
I poked around to see if there were any other likely vegetables. I momentarily considered carrots, but rejected that idea. The purple cauliflower was pretty, but I didn't think the color would help the soup. Ditto for the radicchio and the purple sweet potato.
If I had white or yellow cauliflower, cabbage, or red bell pepper, those probably would have gone into the soup. Asparagus would have been nice. Mushrooms would have been tasty. But I went with what I had.
I simmered the veggies in the milk/water mixture until they were soft, then whizzed them up with the stick blender. I added some buttermilk, cream, and homemade Greek-style yogurt that I had left over. Probably a half-cup of each, but I didn't measure. Let it all simmer gently and tasted again. Hmmm...something missing. I added a little bit of saffron, and that was it. Garnished and served.