When to harvest and how to serve Mooli Radish?

My Mooli Radish are getting a decent shoulder on them. I believe they will grow pretty big without effecting the flavour?

Never grown it before, any suggestions for when to harvest, and how to serve it, would be appreciated.

Do I need to get it out of the ground before the frosts, or will it come to no harm being "left"?

 

I find Mooli a very useful catch-crop after potatoes.
We use them raw, can be grated and mixed with carrot if too strong on their own
Also good in stir fries - give a balance to sweet veg. Great in curries