Freeze your fruit. Begin by slicing the banana and placing it on a small baking sheet or plate lined with parchment paper. Add the blueberries and strawberries to the same plate (store-bought frozen fruit is also an option). Transfer the tray or plate to the freezer and let the fruit freeze completely.
Blend. Once your fruit is thoroughly frozen, combine the milk and yogurt in a large, high-speed blender with a tamper (refer to notes if needed). Add the frozen blueberries, strawberries, banana, and the broken acai puree pieces. Start blending on low speed, using the tamper to push the frozen fruit down and mix as thoroughly as possible. Continue blending on low until the mixture is smooth, adding more liquid only if necessary.
Assemble. Pour the blended smoothie into two bowls. Garnish with your preferred toppings, such as sliced banana, nuts, seeds, granola, and fresh berries. It's best enjoyed immediately.