Prepare all the ingredients (batter ingredients, peel and chop the mango, prepare 12 paper muffin baking cups and a muffin tithen preheat the oven to 180 °C / 350 °F / gas 4, no fan. If you have a convection oven, reduce the temperature by about 20° or follow the manufacturer's instructions.
Whisk the dry ingredients in a medium bowl (flour, baking powder, baking soda, salt).
In a big bowl, whisk all the wet ingredients together (oil, sugar, sour cream, eggs and vanilla extract).
Sift the flour mixture into the wet ingredients. Gently combine the wet ingredients with the dry ingredients until almost combined. Do not overmix the batter! lumps in the batter are ok.
Add the cubed mango, gently fold in the batter with a silicone spatula.
Line the muffin tin with muffin baking cups. Optionally you can brush the cups lightly with oil, to make the peeling off the paper easier.
Divide the batter equally between the baking cups, I like scooping out the batter with an ice cream scoop.
Bake the muffins for 20-22 minutes. They should be golden and a cake tester/bamboo skewer inserted into the center of the muffin should come out clean. Baking time may vary depending on the oven and the muffin tin, that you have used (for example, if you're using silicone baking molds, you may need to bake the muffins just a little longer).
Take the muffin tin out of the oven, instantly take out each muffin of the tin, transfer to a cooling rack. Wait for them to cool down a little, to make the peeling off the paper cups easier.
Make the passion fruit glaze: cut maracuja in half, using a teaspoon scoop out the seeds, using the back of a wooden spoon strain the pulp through a fine sieve (seeds should stay on the sieve and the juice should gather in the cup that is below). To make it easier you can blend the seeds in the food processor and then strain through a sieve. Whisk the passion fruit juice with the icing sugar together, you can add more juice or more icing sugar to achieve a consistency that you like. It should be thick but still pourable.
Drizzle the muffins with the passion fruit glaze and serve. Enjoy!