Put the bread flour and yeast into a mixing bowl and blend them together.
Stir in the water to make a smooth batter, cover and leave in a warm place until swollen and bubbly, about 2 hours.
Measure the plain flour, salt and vitamin C into a bowl, stir to combine then sieve this into the mixing bowl.
Stir into a soft doughy mass and using your hands, knead the dough in the bowl for 50 presses, without adding further flour.
Cover the bowl with another upturned bowl and leave it in a warm place for the dough to double in size, which will take about an hour.
Stand a double baguette tray on a large oven tray OR fold a tea towel into two pleats 38cm/15” long and 5cm/2” deep and lay this on one side of a large oven tray.
Dust the baguette tray, or the inside of the pleats, liberally with rice flour.
Knead the dough in the bowl for another 50 presses, without adding flour.
Cut the dough in half and sprinkle both pieces with rice flour.
Lightly dust the work surface with rice flour and roll each piece of dough into a cylinder 38cm/15” long.
Transfer the dough cylinders to the baguette tin or tea towel pleats, loosely cover and leave to rise in a warm place for 35 minutes and pre-heat the oven.
Put a deep oven tray into the oven, fill it with boiling water and pre-heat the oven, this will make the oven steamy.
If using the tea towel, gently roll the risen baguettes onto the baking tray.
Quickly and carefully make some cuts across the top of the baguettes.
Open the oven door, taking care to avoid any rush of steam, and quickly insert the baguettes. Bake for 25–30 minutes.
Remove from the oven and transfer to a wire rack to cool.