Combine fresh strawberries, sugar, cornstarch and water in a blender. Blast. Heat the mixture and boil it for 2 minutes. Put it in the refrigerator to chill. Cook the puff pastry cups, and while they are cooking chop up strawberries into small pieces until you have a cup. Mix the chopped berries and 1 cup of the chilled strawberry "jam". Poke in the top of the puff pastry to form the cup. Fill the cups. Garnish as desired with whipped cream, chocolate, powdered sugar or sifted cocoa.
You will have about a cup of the strawberry goo left over. Use on ice cream, bread, throw a few tablespoons into a smoothie, dip chocolate in it, put it on a biscuit or shortcake ...