Start by rubbing the zest into the sugar and then add butter; whisking the butter fluffy with the sugar. Add the eggs one at a time and whisk again till fully combined.
Add in your sourcream, mix again, and then sift in your flour and fold the batter carefully. We don't want to overmix.
Transfer the cake into the loaftin with baking paper attached.
Bake in the oven at 185 C for approx 45 minutes to an hour, but please check it after 45 minutes by inserting a toothpick inside the cake. If no crumbs come out, its done.
Let the cake cool down for 15-20 minutes before adding the topping.
Combine the following for the topping: 250 g powdered sugar, 40 g water, 20 g lemon juice, 0.5 tsp yellow food dye. Add more powdered sugar if you want it sweeter.
