Here is a fast and easy recipe for making an ice cold and sweet fruit shake with no added sweeteners.
1 frozen banana (I keep a stock of frozen bananas [very ripe, peeled and individually wrapped in cellophane] throughout the Summer. They are delicious to eat just like that, as if a popsicle. Another easy and most delicious frozen fruit are grapes. Again, the riper the better; wash and freeze in tupperware as they are. Eat them just like that. Frozen grapes are a great Summer treat as are frozen bananas.
1 equal proportion of any type of fruit: e.g. watermelon, strawberries, a large fresh peach, one or two kiwis, a handful of mulberries (or any berry, for that matter). I usually use just one type of fruit at the time, but some combinations work very well. Experiment as you like here but the ratio of banana to all the other fruit should be 1:1. The idea here is that the frozen banana offers the shake perfect consistency and the other fruit add the desired flavor and color.
(Optional, a minimal amount of milk to help the blending.)
You can also add some raw almonds if you would like to add some protein to the shake.
First, blend the fresh fruit (and milk and almonds) and then add the frozen banana in quarters until all is a smooth consistency. Pour in a glass and serve (makes about 16 oz.). You can place this in the freezer for 15-20 minutes if you would like it colder.