Set aside 1 cup of the most attractive strawberries for garnish.
Hull and slice the remaining 3 cups of strawberries.
In a saucepan, combine sliced strawberries, sugar, and lemon juice.
Cook over medium heat, stirring occasionally, until the strawberries release their juices, about 5 minutes.
In a small bowl, whisk together cornstarch and water to create a slurry.
Slowly pour the cornstarch mixture into the strawberry mixture, stirring constantly.
Continue cooking until the mixture thickens, about 2-3 minutes.
Remove from heat and allow to cool completely.