Much loved by Asian cultures, daikon radish is a great healthy alternative if you are cutting carbs. Not only is it a successful replacement, on it's own daikon and all radishes have wonderful health giving properties.
The leaves are edible as well as the root, so consider throwing them chopped into your mash, or mixing with other green leaves in stir fry. The root can be sliced raw into salads, grated finely to serve alongside fish and seafood, or even cut into chunks and braised. The sweetness is accentuated when cooked and the slices absorb the flavour of your dish.
To get the ball rolling here is a recipe for Buri Daikon. A Japanese braise using yellowtail kingfish. I'm sure if you wish to make this vegetarian, you could easily leave the fish out, or even add some firm tofu and mushrooms.