Preheat the oven to 350℉
To a bowl, add the flour, corn starch, salt, baking powder, baking soda, and cardamom powder. Combine thoroughly.
Mix the cardamom powder and sugar and set aside.
To a bowl, add the sugar, tangerine juice, and thick yogurt. Combine well until the sugar dissolves completely. Then, add the oil, vanilla extract paste, and mix thoroughly.
Add the dry ingredients in three or four steps to the wet ingredients, beating thoroughly. Fold in the tangerine zest.
Grease a 6-inch baking pan. Sprinkle the cardamom sugar on the bottom and line the bottom of the tray with thin slices of tangerines
Pour the cake batter on top. Tap a couple of times and place it into the oven to bake for 28-29 minutes (check with a toothpick if the cake is done).
Remove from the oven and cool completely.
Carefully, transfer the cake to a platter. Serve slices of delicious tangerine upside down cake.