Put sugar and water in a medium saucepan and place over medium heat. Cook until the sugar is dissolved and the mixture comes to a boil.
Let the mixture boil for 2-3 minutes and then add berries lemon juice, cornstarch and salt.
Let mixture come to a boil and starts to thicken.
Take pan off of heat and add butter. Lightly stir in butter until it melts.
You can use mixture immediately or let it come to room temperature and store it for later use.