To make the sauce, in a small saucepan combine the strawberries, sugar, lemon zest and juice and cook over medium-high heat, stirring occasionally. Cook until the fruits begin to break down and release their juices at the same time mashing a few berries to help in the process. Continue to cook until the sauce thickens roughly 10-12 minutes or to your desired consistency. The sauce will continue to thicken as it stands. Leave to cool completely before using. Store in the refrigerator if not using right away. Enjoy!