My favorite way of eating it is as a sandwich with a fried egg and a few drops of soy sauce or pork floss. I've also tried spreading a little bit of fermented bean curd (豆腐乳) on, which is also very delicious. Other ways like deep frying your mantou before dipping into sweetened condensed milk is also very good. But basically you can use it as a sandwich bread and stuff whatever you like in it, or just eat it by itself with a bowl of congee or soymilk.