Step 1

Place blackberries, lemon juice and sugar in a large saucepan.

Step 2

Cook over medium heat, stirring frequently until it comes to a boil.

Step 3

Continue to boil and stir for 10 minutes.

Step 4

If you desire a thicker sauce, make a slurry of the cornstarch and water and add to boiling berries. Cook until thickened.

Step 5

Remove from heat and cool. Store in the refrigerator until ready to use.