Chop the strawberries and freeze them on a flat surface (it can be a ziploc bag laid on its side). The idea is that they don't freeze in a block so that your blender or food processor doesn't suffer in the process.

Put everything in the blender or food processor until smooth.

I didn't sweeten mine because the bananas bbring enough sweetness for me, but you could also add maple syrup, honey, sugar or sweetener.