Strawberries left in sugar for half an hour to draw out their juice, then blended with cold milk. The maceration is what makes it taste of strawberry rather than of pink milk. Five servings.
The half hour in sugar is the step worth keeping. Sugar draws juice out of cut strawberries by osmosis, and that juice is concentrated strawberry flavour that would otherwise stay locked in the fruit. Blend them straight from the fridge instead and you get something pink and mild. Everything cold. Cold milk, cold fruit, and if you can, a cold blender jug. A milkshake blended warm and then chilled is never as good as one that was cold to begin with, because the ice crystals are different and it separates faster. Sieving is optional and the recipe says so. Strawberry seeds are small enough that most people do not notice them; pass it through if you want it completely smooth.