Measure out 1 cup (150g) of frozen strawberries. Peel your banana and slice it into chunks. If using a pre-frozen banana, break it into 3-4 pieces with your hands. If using a fresh banana, peel and slice it before freezing overnight on a parchment-lined tray.
Pour 1 cup (240ml) of your chosen liquid (almond milk, oat milk, or coconut milk) into the blender first. This helps the blades spin freely. If using honey, maple syrup, vanilla extract, or a pinch of salt, measure them out now.
Add the frozen banana pieces on top of the liquid, then add the frozen strawberries on top of the banana. If adding any optional ingredients (honey, vanilla, protein powder), add them on top of the fruit.
Secure the blender lid tightly. Start blending on low speed for about 10-15 seconds, then gradually increase to high. Blend on high for 45-60 seconds, or until the smoothie is completely smooth with no visible chunks or streaks of fruit.
If the blender struggles or the frozen fruit isn't moving, stop the blender, remove the lid, and use a spatula to push the contents down toward the blades. Replace the lid and blend again. For an extra-smooth finish in a standard blender, blend for an additional 30 seconds after it looks smooth.
Remove the lid carefully and taste the smoothie using a long spoon or straw. If you want it sweeter, add 1 tablespoon of honey or maple syrup and blend again for 10 seconds. If too thick, add 2-3 tablespoons (30-45ml) of your liquid base and blend briefly. If too thin, add a few more frozen strawberries or a small piece of frozen banana and blend again.
Pour the smoothie into a tall glass, holding the blender at an angle and pouring slowly to prevent spills. If desired, garnish with a fresh strawberry on the rim, banana slices, or a small sprig of fresh mint. Serve immediately with a straw or long spoon.