1. Cook the flour with the corn oil for 10 minutes over medium-low heat, stirring often.
2. Slowly incorporate the water and liquid stevia, stirring constantly. Bring the pot to a boil over medium heat, reduce the heat to low, and simmer, covered, for 20 minutes, stirring often. Pour the mixture into an oiled 9-inch pie tin and chill.
3. Top the grain layer with the fruit and nuts, cut the porridge into 6 wedges, and serve.