Light breakfasts have never sustained me, so I prefer a fry-up or pancakes. Congee (savoury rice porridge) is actually pretty good!
Here in Slovakia, I'm eating a more balanced breakfast ("raňajky") of smoked sausage, cheese, bread, tomato, sauerkraut and mustard or gherkins. With tea or coffee.
Grammar note: "What does your usual breakfast consist of?" The verb here is "consist", so you need "do/does" to make it a question, not "is".
I expect this phrasing to be used by a nutritionist or doctor, but it is still very familiar. The common way of asking is, "What do you usually have for breakfast?"