For the Cherry blueberry strudel filling, boil the following:
500 gms. of frozen blueberries
250 gms. of frozen pitted cherries
3/4 cups of granulated sugar
3 tbsp. cornstarch mixed in 1/4 cup of water
Once it starts to boil, bring the temperature down to medium and constantly stir it until very thick.
Turn off the heat and let the mixture cool down to room temp.
Then add the juice of half a lemon.