Place flour and salt into a bowl and mix well and make a well in the centre.
Add the yeast and sugar into the lukewarm water and mix until all dissolved.
Slowly incorporate the flour and yeast solution together until you have a rough dough.
At this stage the flour has basically absorbed the water but we have not developed the gluten protein to make it a smooth firm dough.
Lightly flour a work surface and tip the dough out of the bowl and begin to knead. The longer you work the dough the firmer and smoother it will become.
A good way to check it is to take your index finger and gently press the dough - if it springs back, it’s ready! If the indentation stays, work the dough longer.
When ready, place back in the bowl and cover with cling film. Allow to rest at room temperature until doubled in size (normally 35 -45 minutes).
Tip it out of the bowl and knock the dough back just for a minute or two then roll out to approximately 3 cm thickness.
Place on a flat non-stick baking tray, lining the centre of the dough with the cooled caramelised onions, grated cheese, tomatoes, olives or whatever you have, and a scatter of parmesan cheese.
To shape the bread, fold in the top corner to meet the centre and fold the opposite corner on top.
Repeat this process for the other corners. You should be left with a diamond in the middle of the bread where the onions and cheese are exposed.
Drizzle with olive oil and a good pinch of sea salt crystals and sprinkle of fresh thyme.
Cover with cling film again and prove the bread for 15-20 minutes or until the bread has again just under doubled in size. (Proving should be quicker this time as yeast has been activated in the resting stage.)
Bake in a preheated oven 190c (fan assisted) for 18 minutes.