Dissolve sugar in warm water, add yeast and stir until dissolved and a thick froth appears, 1 to 2 minutes.
Place flour and salt in a large bowl. Make a well in the centre and pour in yeast, olive oil and enough lukewarm water to make a soft dough. Turn out onto a floured wooden board and knead until dough is dimpled and satin smooth.
Place dough in an oiled and warmed mixing bowl, roll it around in the bowl to coat with oil (this will prevent a crust forming).
Cover with a tea towel and leave to rise in a warm place until doubled in size, about 1 1/2 hours.
Punch down dough and knead once or twice. Roll dough out into a 24 x 30 cm rectangle. Place on a floured baking sheet.
Leaving a 10-15 mm rim around edge, scatter olives, herbs and lemon peel over half the dough.
Fold over remaining half of dough and press edges together to seal.
Using a sharp knife, cut 4 cm diagonal slits in the dough. Brush with olive oil and sprinkle coarse sea salt over. Leave to rise for about 30 minutes.
Bake at 240-250 ºC for 15 to 20 minutes. Serve hot.
Makes 2 loaves