In a medium-sized pan, heat strawberries over medium heat until bubbly. Take a fork and smash strawberries. Add in sugar and lemon juice, stirring occasionally. Let the strawberries cook down for several minutes. In a small bowl, mix together corn starch and water. Pour corn starch mixture over strawberries and continue mixing and cooking until mixture has thickened to desired consistency (add more water if too thick, more starch if too runny). Remove from heat and let cool.
