Dissolve yeast in warm water and let it stand till foamy ( about 5 minutes)

Add the sugar, oil, flour and salt. I use a stand mixer so with the dough hook knead at low speed until smooth and elastic (about 8 to 10 minutes)

Remove the dough from the bowl and transfer to a lightly oiled bowl and cover with plastic wrap. Let the dough rise in a warm spot until it doubles in size ( 11/2 to 2 hours).

You may need to add extra flour while kneading so the dough will pull away from the sides of the bowl.

Transfer the dough onto a lightly oiled surface and lightly dust your hands and roll out balls to 1 inch in size then cover with a kitchen towel for about 10 minutes.

Heat oil 3 to 4" deep in a heavy kettle or deep-fat fryer to 375 degrees.

Transfer doughnuts to the kettle of fat on a broad spatula, using care not to alter shape. (If possible, place board of doughnuts near frying kettle.) Slip into hot fat.

Add only enough doughnuts at a time as can float on the fat or that can be turned easily. Turn doughnuts as they rise to the surface.

Fry 2 to 3 minutes, or just until doughnuts are a golden brown.

Lift doughnuts from fat and drain on paper towels and then roll them whilst still hot in a bowl of sugar and ground cinnamon. Place on a rack to cool.

Crush the strawberries with a masher and mix thoroughly with the cream cheese.

Fill a piping bag with the filling.

Pierce a hole in each donut and using a piping bag squirt the filling into each donut.