Put the flour, yeast, sugar and 1 tsp sea salt in a large bowl and stir to combine. Stir in the water and the oil to bring everything together into a firm, smooth dough (you may need to add a little more water). Tip the dough out onto a lightly floured work surface and knead for 5 mins until the dough is smooth and elastic. Return to the bowl, cover and leave in a warm place to prove until it has doubled in size, about 1 hr.