Peel and core apples then cut into small chunks. In a large saucepan, bring apples, cinnamon stick, and water to a boil and simmer until apples are tender when poked with a fork, about 15 minutes. Add strawberries and cook 5 minutes more. Remove from heat. Press the mixture through a sieve over a bowl. Taste, and if sugar is needed, add now while the mixture is still warm. Refrigerate until ready to serve.