Add the vanilla soy milk, frozen mango, frozen banana, oats and spices to a blender.
Blend on high or use the smoothie program of your blender. Let it run for at least 30 seconds to make sure the oats are as finely ground as possible.
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Notes
If you don't have vanilla-flavored milk, use plain soy milk and add ¼ teaspoon of vanilla extract.
I recommend quick-cooking oats because their thin flakes blend more easily and provide a smoother texture.
If you're using rolled oats, try blending them first and adding the other ingredients afterward. Alternatively, soak the oats in water overnight. This softens them and makes them blend in seamlessly.
Use a glass blender jug to avoid turmeric stains.
Add more milk for a thinner smoothie.
Adding pepper increases the absorption of the active compound curcumin found in turmeric.