Although the Day Lily has rhizomes too, at this time of year they are very tough and fibrous, not particularly good for eating. The tubers though are very good eating. Right now they have a stronger flavor than in the spring but even so, the flavor is very mild.
To make the most of the flavor, it is best to pair it with other light flavors like white fish. The flavor is a little like potato with a faint hint of leek.
These little tubers can be boiled for 15-20 mins to achieve tenderness. Best par boiled and then roasted until the skin is crispy or simply sliced and sauteed until golden brown. They also make a decent puree although it takes a lot of tubers to make a good quantity.
We keep the entire base of the plant together so the tubers are in one neat cluster which makes them easy to wash quickly, especially with a vegetable brush (note the cleaned tubers as pictured above). We are supplying them unwashed (also pictured), with a very thin coating of mud to keep them as fresh as the moment they were harvested. There are no poisonous parts of the Day Lily so the whole thing can be used after washing.