Combine the yeast, water, and sugar in a small bowl and allow to proof for 5 minutes or so.
Meanwhile, mix the bread flour and salt in a large mixing bowl or the bowl of a stand mixer.
Add the proofed yeast mixture to the flour mixture and stir with a spoon until well combined, then knead the dough right in the bowl, or turn it out onto a lightly oiled or floured counter and knead for 10 to 12 minutes, or until it's smooth and bouncy.
If using a stand mixer, mix with the flat beater, then switch to the dough hook and knead for 8 minutes on speed 2.
Place the dough in an oiled container, turning it to cover all surfaces.
Cover it with a clean dish towel and let it rise at room temperature about 30 to 45 minutes, or until it has doubled.
Turn the dough out onto a lightly oiled or floured counter, and flatten it into a rectangle 12" by 16".
Divide it in half--making two rectangles 12" by 8".
Starting with one rectangle and beginning on a 12" side, roll it tightly, pinching the dough together to form a seam when you reach the end.
Then roll the dough over with that seam side down, and gently roll it back and forth, using your hands to taper the ends.
Repeat with the other portion of dough.
Place the baguettes on a large parchment lined or greased cookie sheet and make deep diagonal slashes with a very sharp knife every 2 or 3 inches along the length of the loaf.
Lightly cover with plastic wrap or a dish towel and allow to rise at room temperature until double, about 1 hour, but start preheating your oven to 375ºF after about 30 minutes.
When the loaves are ready to bake, beat the egg yolk and water together with a fork, and gently brush the mixture all over the risen loaves.
Bake for 20 to 25 minutes, or until golden brown and an instant-read thermometer reads 190ºF to 200ºF when inserted into the middle of the loaves.
Turn out onto a rack and allow to cool for 15 to 20 minutes before cutting.
To freeze, cool the bread completely, then wrap tightly in plastic wrap followed by foil.