Lightly oil a 2¼ litre/4 pint square plastic container with olive oil. (It’s important to use a square tub as it helps shape the dough.)
Put the flour, salt and yeast into the bowl of a freestanding mixer fitted with a dough hook (don’t put the salt directly on top of the yeast). Add three-quarters of the water and begin mixing on a slow speed. As the dough starts to come together, slowly add the remaining water, then continue to mix on a medium speed for 5-7 minutes, until you have a glossy, elastic dough.
Tip the dough into the prepared tub. Cover and leave for 1 hour, or until at least doubled in size.
Dredge a linen couche with flour and lightly dust the work surface with flour.
Carefully tip the dough onto the work surface. Rather than knocking it back, handle it gently so you can keep as much air in the dough as possible. (This helps to create the irregular, airy texture of a really good baguette.) The dough will be wet to the touch but still lively.
Divide the dough into 4 pieces. Shape each piece into an oblong by flattening the dough out slightly and folding the sides into the middle. Then roll each up into a sausage – the top should be smooth with the join running along the length of the base. Now, beginning in the middle, roll each sausage with your hands. Don’t force it out by pressing heavily. Concentrate on the backwards and forwards movement and gently use the weight of your arms to roll out the dough to 30cm/12in long.
Lay a baguette along the edge of the linen couche and pleat the couche up against the edge of the baguette. Place another baguette next to the pleat. Repeat the process until all 4 baguettes are lined up against each other with a pleat between each. Cover the baguettes with a clean tea towel and leave for 1 hour, or until the dough has at least doubled in size and springs back quickly if you prod it lightly with your finger.
Preheat the oven to 240C/220C Fan/Gas 9 and put a roasting tray in the bottom of the oven to heat up.
When the baguettes are risen, remove them from the couche and dust lightly with flour. Slash each one 4 times along its length on the diagonal, using a razor blade or a very sharp knife. Transfer to a large baking tray.
Fill the heated roasting tray with hot water, to create steam, and put the bread into the oven. Bake for 20-25 minutes, or until the baguettes are golden-brown and have a slight sheen. Cool on a wire rack.
A couche is a heavy linen mat used to shape bread while it proves. It absorbs some of the moisture from the outside of the dough, this helps develop a skin, keep the shape and develop a crisp crust.