Almost every week during winter, I bring home quince and celeriac from the local market here in Istanbul. In addition to sunchokes, cabbage and pomegranates, they are my favorite winter produce. Here is a very simple and delicious soup using sweetness from quince and spicy body from celeriac. You could probably add half a cup of cream towards finishing the soup to make it creamier; or add a starchy potato while cooking to make it denser. I really loved it this way. Very simple and flavorful!
olive oil (you could skip butter and use 2 tbs olive oil if you like)
celeriac (cut into chunks)
quince (cut into chunks)
water (or vegetable broth)
pepper (white pepper if you do not want the specs:))