Sift the flour into a large bowl, mix the salt and yeast with the flour.
Stir the water into the flour mixture while warm to the touch until the dough separates from the bowl.
Form the dough into a ball and knead well by hand on a floured work surface for 10-15 minutes until it bubbles.
Place the dough again on the bottom of the bowl dusted with flour. Cover with a wet kitchen towel and let rise in a warm place for about 3/4 hour, until doubled in size.
Divide the dough into 4 parts of 300 g each. Knead each part well and then turn it into 40 cm long rolls, place them on a greased baking sheet.
Cover with a kitchen towel and let rise for another 1/2 hour. Brush with the egg and score the surface diagonally.
Preheat the oven to 220 °C.
Place an ovenproof dish with boiling water in the oven and bake the baguettes on the 2nd rack from the top for 35 minutes.