Peel and chop the rutabagas, turnips, carrots and daikons into similar size pieces and put into a large bowl.
Peel and cut the onions into wedges and add to the bowl.
Add the salt, oil and pepper toss and pour on a sheet tray.
Cook 25 minutes, then use a spatula to turnt the veggies over. Put back into the oven to finish cooking, about 20 minutes. The outside should begin to caramelize and the insides will be tender.
Remove from oven and use the spatula to put into a large bowl, toss with the fresh thyme leaves.