Celeriac is ugly. This root vegetable has a tough dirty exterior and a creamy white interior. Its mess of roots have been trimmed before it reaches the produce aisle, but there is still evidence of the reaching that once went on.
My first introduction to celeriac was in a soup. I was working in a British tearoom and the chef made a puréed root vegetable soup, which I thought was just carrot soup - by appearance. But it tasted more complex than plain carrot soup. When I learned that the slight celery flavor came from celeriac, I was determined to copy that recipe again and again. Today I was in the mood for a chunkier vegetable soup, so I puréed the cooked celeriac, but kept the carrots in chunks and added bite-size bits of cauliflower.
You will need a large sharp knife to cut your celeriac. I used my new America's Test Kitchen-endorsed Forschner Victorinox chef knife. I have a Wüsthof standby, but I couldn't resist trying the Victorinox after all the talk. And it's only $30. So far, I like how it handles. Perhaps I should have had it on hand a few months ago when a date offered to come over and cook me dinner. He was a trained chef and I anticipated a great meal. (He mentioned a few Thai specialties.) When he showed up, he was empty handed. I looked at him blankly, expecting him to pull produce from behind his back at any moment, maybe a jar of curry paste... After we went to the grocery store, I made cocktails and sat back to watch the chef in action. He proceeded to instruct as he cooked, condescending my knowledge of food preparation and criticizing my kitchen wares, including my knives. The meal wasn't memorable. (He made penne with red sauce.) And obviously the company was sub par. I have savored my kitchen ever since that night. My knives, my cutting board, my pots, pans, wooden spoons... They are good enough for me. You should know that I have dated two other chefs in my adulthood. Both of them always came prepared. And both of them cooked without offending their guests. Is that too much to ask?
Back to the soup. You will need both a chef's knife to chop and a paring knife peel the celeriac. (Unless you have a super sharp potato peeler.) I chopped it into 1/2" chunks, placed them in a saucepan and covered them with water, salted, brought to a boil, then simmered ~10 mins. While the celeriac was cooking, I chopped up a small yellow onion, a few carrots, and 1/2 a large cauliflower and sautéed them in olive oil at the bottom of a stock pot. When the onions were translucent, I added water to cover and boiled until the veggies were just barely soft. (Use broth/stock if you have it.) In batches, I puréed the celeriac and added it to the stock pot with the other vegetables. (If you don't have a food processor, use an electric mixer like you would to make mashed potatoes.) I added a couple cloves of crushed garlic and a bit of cumin for flavor and color. Then I grabbed a spoon to taste.