With the rack in the middle position, preheat the oven to 180 °C (350 °F). Generously butter fifteen 75 ml (1/3 cup)-capacity mini Bundt pans. Set aside.
In a bowl, combine flour, cornstarch, baking powder and baking soda. Set aside.
In another bowl, beat sugar, egg and orange zest until it triples in volume and forms a ribbon. At low speed, drizzle in oil. Add dry ingredients alternately with orange juice and yogurt.
Spoon 45 ml (3 tablespoons) of batter in each mould. Bake for about 20 minutes or until a toothpick inserted in the centre of the cake comes out clean. Let cool for 5 minutes and unmould. Let cool completely on a wire rack.
The batter can sit while you bake the first batch. Mini-Bundt pans are part of the Ricardo accessory collection. You can also use muffin cups.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.