Dissolve yeast in a small bowl in 1/2 cup warm water. Stir and set aside until it foams, about 5-10 minutes.
Combine (most of) flour and salt in the bowl of a stand mixer with dough hook attachment. Add yeast mixture and remaining 1 1/2 cups warm water. Knead on speed #2 until the mixture is combines well and dough is no longer sticking to the bowl, adding more flour in small amounts as needed. Knead until smooth.
Take bowl from mixer and cover with a damp towel. Let rise at room temperature for about an hour or longer, until doubled in volume. It may take 2-3 hours depending on the season and where you live.
Punch down the dough and knead a few times on a floured surface. Cut into 4 equal pieces and roll into long thin loaves. Use a rolling, squeezing, pulling technique.
Transfer loaves into a baguette pan or a lightly oiled large baking sheet or 2 loaves onto each of 2 baking sheets. Let rise again until nearly doubled. Cover very carefully with oiled plastic wrap if desired, but that is optional. Second rising normally takes 45-60 minutes.
Preheat oven to 450 degrees on the bake setting, not convection bake. Ensure rack is in middle of oven or if using two baking sheets, the lower and middle location. Place a metal pie plate on the oven bottom under the lowest rack and add 1 ½ cups boiling water.
Beat egg and add cold water. Brush over loaves. OR, spritz gently with water. Using a very sharp knife, slice diagonal slits in the tops of loaves.
Bake for 15 minutes at 450° then reduce heat to 400 without opening the door. Bake another 5-10 minutes until loaves are golden brown. If desired, switch to convection bake for last few minutes if loaves aren't browning enough.