4 oranges to squeeze or approximately 250ml freshly squeezed orange juice
250ml soy milk (or rice milk)
couple of handfuls of (frozen) raspberries or strawberries
4 tablespoons of instant oatmeal powder
2 tablespoons of flax seeds
couple of ice cubes (you could leave this out if you are using frozen fruits/if some of your ingredients have been refrigerated)
Put everything in a blender and blend! This should make about a litre of it. I usually have it all by myself but if that's too much (it's really filling) you could also share it with someone else or put it in the fridge to have the rest the next day.
I use it when I have exams as oatmeal gives you a steady supply of carbohydrates so it's great to keep your brain going. The flax seeds are great for the brain in the long run. (I just can't handle oatmeal by itself.)