For the doughnuts, place all the ingredients into a large bowl (except the sunflower oil) with three tablespoons of water.
Stir with your hands to make a dough.
Gradually add another another tablespoon of water and massage in the bowl for four minutes.
Tip the dough onto a lightly floured surface and knead well for 10 minutes, or until the dough is smooth and elastic.
Place into a bowl and leave to rise for 40 minutes, covered with a damp tea towel.
Tip the dough out, again onto a very lightly floured surface.
Divide the dough in half.
With a floured rolling pin, roll out the dough quite thinly to about 1cm/½in thick. Cut into rounds using an 8cm/3¼in straight sided round cutter, then use a 2cm/¾in cutter to cut holes out of the middle.
Spin each doughnut on your index finger to expand the hole.
You should be able to cut out about eight doughnuts from this dough. Place all circles onto an oiled baking tray, loosely cover with cling film, not allowing it to touch the top of the doughnuts and leave to rise for 30 minutes.
Preheat a deep fat fryer, filled with sunflower oil to 180C/350F (Caution: hot oil can be dangerous; do not leave unattended.)
Drop each doughnut in separately, cooking each side for about a minute or until golden-brown. Remove with a slotted spoon and place onto a plate lined with kitchen towel to soak up the excess oil.
Leave to cool.
For the icing, gradually add 25ml/1fl oz of cold water to the icing sugar. It will eventually turn into a thick paste. Stir in the lemon zest.
When the whole doughnuts have cooled, brush the tops of the doughnuts with the icing. Sprinkle over a little more lemon zest.
Leave to set on a cooling rack, to cool completely.