Add the yeast to about a third (200ml) of the warm water. Leave to froth up in a warm place.
Meanwhile, mix the flour and sea salt together.
If the flour has been stored in a cold place, warm slightly then pour the yeasty liquid into the flour, followed by the oil, and gradually add all the remaining water. Knead well for about 10 minutes to a polished, silky soft dough.
Cover with a damp linen cloth and allow to stand for 20 minutes.
Meanwhile, preheat the oven to 220°C /428°F / Gas Mark 7.
Warm the 2 baking trays or 3 small flower pots (about 5 1/2" diameter) then lightly oil. Divide the dough into 2 (for trays) or 3 (for flower pots) equal pieces, knead out the air and place on the trays/in flower pots.
Recover with the damp linen cloth and leave to rise in a warm, draught-free place (about 80°F is ideal) for about 3/4 hr until the dough has doubled in size.
Bake for 35 - 40 minutes. Turn out the bread and tap the bottom. If it sounds hollow - the bread is cooked. If knocking the bread produces a dull thud - return it to the oven, turned upside down for a little longer.