In a warm bowl (rinse in hot water then dry thoroughly), mix together the flour, salt, caster sugar and yeast.
In a jug, combine the chilli jam and olive oil with 400ml warm water, then stir this into the flour mixture to make a soft dough. Knead for 10 minutes on a lightly floured surface until smooth and elastic.
Oil 2 x 23cm cake tins. Divide the dough into 2 pieces and roll each one into a 23cm circle, then place in the tins.
Using your fingertips, make deep dimples over the surface of the dough. Cover with cling film and leave in a warm place for 30 minutes until doubled in size.
Preheat the oven to 230ºC, fan 210ºC, gas mark 8. Remove the cling film, drizzle each focaccia with olive oil, sprinkle with a pinch of sea salt and bake for 30 minutes until golden and cooked.
Leave to cool in the tins slightly, then remove and place on a wire rack. Slice into wedges to serve.