In a blender, combine the sliced strawberries, lemon juice, and sugar. Blend on high until smooth and the sugar is fully dissolved.
Add the ice cubes and water to the blender, and blend again until the mixture is slushy and well combined. Adjust the consistency by adding more ice if desired.
Taste the lemonade and adjust sweetness by adding more sugar or lemon juice as needed. Blend briefly to combine any additional ingredients.
Pour the frozen strawberry lemonade into chilled glasses.
Garnish each glass with a lemon slice and a sprig of fresh mint for an added touch of freshness. Serve immediately.