Add the orange juice, banana, frozen fruit and spinach to a high-speed blender.
Blend on high until perfectly smooth. You can adjust thickness by adding more orange juice if you prefer.
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Notes
Use baby spinach for a less fibrous texture.
If you don't have a powerful blender, make sure to run the frozen fruits shortly under warm water. This will slightly soften them and make the blending process easier.
Freeze your smoothie mix. Cut fresh mangos, pineapple and bananas into small chunks. Add the right amount of each to a zip bag with the spinach and store them in your freezer. When you want a spinach smoothie you can pop everything in your blender with orange juice and you're done.
You can replace the orange juice with coconut water to reduce the sugar content of the smoothie.