In a mixing bowl, combine all-purpose flour, sugar, cornstarch, and water. Whisk until smooth.

Add vegetable oil and mix well.

Heat a frying pan over medium heat and lightly grease it.

Pour a ladle of batter into the pan, swirling to form a thin pancake. Cook for 1-2 minutes until edges lift, then flip and cook for another minute.

Repeat with remaining batter, stacking pancakes on a plate.

In a bowl, mix the whipped cream with powdered sugar until well combined.

Fold in the diced mangoes gently.

Place a pancake on a plate, add a generous spoonful of the mango filling in the center, and fold the pancake over to enclose the filling.

Repeat with remaining pancakes and filling.