In a mixing bowl, add oil, orange juice, condensed milk, sugar, and mix well.
Once mixture is light and fluffy, add vanilla, orange zest, and mix again.
Sift baking powder, flour, baking soda, and pinch of salt over wet ingredients and mix.
Grease 6-inch round pan, dust with flour, and pour batter into pan. Place steamer rack and water into pressure cooker. Place baking pan on rack.
Close and lock lid, set pressure cooker to "bake", adjust time to 40 minutes, and press "start/stop". When done, quick release and make sure all pressure is released before opening lid. Carefully open lid and remove cake. Cool, slice, and serve.
