First, in a bowl, mix the egg, oil, sugar, sour cream or crème fraiche and juice until well combined.
Sift flour, baking powder and possibly baking soda in a second bowl and quickly fold into the liquid mixture.
Peel the tangerines, cut into small pieces and fold in carefully.
Divide the batter among 12 muffin cups.
Bake the muffins in the preheated oven at 200 °C for 25 minutes on the 2nd rack from the bottom.