Blend the strawberries, sugar, and water in a blender until smooth. Pour the purée into a heavy-bottomed saucepan. Bring the pot to a rolling boil over low to medium heat for 5 minutes for the sugar to melt. Stir consistently so that it doesn’t scorch.
Whisk together the cornstarch, 2 tablespoons of water. Turn off the heat and whisk in the cornstarch mixture, strawberry extract, and red food coloring if using. Allow the syrup to cool before storing or serving.