How to give frozen puree foods?

Hi, my little boy is just going onto solids now and i have been advised by so many people that the best way is to steam a batch of fresh veg and then freeze it in ice cube trays. this is what i have done but i was wondering, how do other people thaw and warm up the veg when you want to use it?? some people have said thaw it in the fridge then heat up in microwave, others have said immerse a bowl of hot water till thawed and warm....just wondering what the majority of people on here do. thanks xx