Mix together the flour, sugar, yeast and salt in a bowl and make a well in the middle.
Mix the oil into the warm water and pour into the well in the middle of the bowl.
Stir the flour gradually into the well bringing it in a bit at a time from the side of the bowl.
Get the dough out on a floured worktop and kneed for 5-10 minutes until smooth and elastic.
Grease a clean bowl with olive oil and put the dough into this, covering with an oiled sheet of cling film.
Place somewhere warm (I put mine in the airing cupboard) and leave to rise for about an hour.
Preheat the oven to 220’C
In the meantime toss the tomatoes, onions and garlic in the olive oil and roast in the oven for 15 minutes.
Remove and stir in the tomato puree and the salt and pepper and then return to the oven for a further ten minutes. Remove and to the side until needed.
Place your peppers under a hot grill on or a naked hob flame and carefully turn regularly until black and charred all over. Once blackened, run under a cold tap and rub off the black skin. Discard the top and the seeds and tear the flash into thin strips.
When your dough has doubled in size, bang it out onto a floured worktop and kneed it for about 2 minutes.
Roll out the dough so it is about 2-3mm thick and square shaped and then smear the tomato puree all over it.
Top with the tuna, capers, peppers and cheese.
Take one end and start to roll it towards the opposite side. Once you have rolled up all the dough seal the ends by pinching them together.
Place on a greased and lined baking tray with the seal underneath and brush with oil before sprinkling a little extra flour over the top.
Bake for 25-30 minutes until golden brown and crispy.
Remove from the oven and leave to cool for a couple of minutes before carving.