Sift the flour, baking powder and salt into a medium bowl. Stir in 1 tablespoon of peanut oil and water using a fork. Divide into 4 pieces, and form into rounds. Set aside.
In a saucepan, stir together the sugar and cornstarch. Stir in pineapple and juice using a wooden spoon. Bring to a boil over medium heat. Boil for 1 minute, stirring constantly. Set aside to cool slightly.
Heat the peanut oil in a large deep skillet to 385 degrees F (195 degrees C). Roll out the balls of dough on a lightly floured surface to about 8x5 inch rectangles. Cut into four smaller rectangles. Fry a few pieces at a time in the hot oil until they puff like pillows, about 1 minute. Turn over and fry until browned on the other side. Remove to drain on paper towels.
While the pillows are still hot, make a slit along two connecting sides of each one. Open up and fill each one with a rounded tablespoonful of the pineapple filling. Dust with confectioners' sugar and serve warm.