In a small bowl, combine the yeast, 2 tablespoons sugar, and ¼ cup warm water. Let stand for 5 minutes until the yeast is foamy.
Sift 4½ cups flour and salt into a large mixing bowl. Make a well in the center of the dough and drop in the eggs, oil, remaining 1¼ cups water, ½ cup sugar and yeast mixture. Work the liquids into the dough mixture with your hands.
Turn the dough onto a floured board (or silicone mat), and knead until smooth and elastic, 5 to 8 minutes. Place in a mixing bowl and brush the top with additional oil. Cover loosely with a clean dishtowel and let sit in a warm place to rise for one hour.
Punch down the dough, cover and let it rise again until it has doubled in bulk.
Turn the dough out onto the floured board. Divide the dough into 3 equal parts to make one large loaf, or six equal parts to make two smaller loaves.
Flour your hands, then roll each piece of dough into a rope so that they are all of equal length. Braid and place loaves on greased cookie sheet. Cover and let rise until double in size.
Preheat the oven to 375 degrees F. Brush the bread with egg yolk and sprinkle with poppy seeds (if desired). Bake 38 to 45 minutes, or until golden brown.
Notes
You can make two smaller loaves, if desired. Cooking time would be slightly less.