In a blender, combine concentrates, strawberries and sugar and puree until smooth.
Stir in water (this recipe will fit perfectly in a 4L ice cream pail if you have an empty one laying around).
Freeze. I like to do this in smaller 1-2 cup containers so it's easy to take out 1 or 2 servings, but you can freeze it in one large batch if you desire.
Remove from the freezer 1-2 hours before serving (depending on the size of your containers -- smaller will thaw more quickly). Spoon into glasses and fill cup with lemon lime soda or sparkling water.