In a jug combine 150ml of the warm water, yeast and sugar and leave for about 10 minutes in a warm place until foaming.
Combine the flours and salt in a mixing bowl (or mixer). Pour in the yeast water as well as the remaining water (warmed to hand temperature).
Mix well and knead on a floured work surface until stretchy and elastic, or use the dough hook on a mixer for about 10 minutes.
Chop the chorizo sausage into 1cm thick slices and then quarter them. Chop the onion and the mozzarella. Add to dough mix and fold and mix (gently) for a few seconds (so as to not to break up the cheese too much).
Place in a lightly oiled bowl and leave to rise for at least an hour covered and somewhere warm. Punch down the dough then transfer to a greased shallow loaf tin and allow to rise for a further 30 minutes.
Preheat the oven to 180 C / Gas 4.
Bake on the middle shelf in the preheated oven for 30 minutes, until golden. Remove from the oven and allow to cool before slicing and serving.