In a medium bowl, mix the yeast, 1 tsp of the sugar, and 1 cup of lukewarm water until combined. Sprinkle with 1 tbsp of the flour. Cover and let stand in a warm place for 10 to 15 minutes, or until frothy.

Sift the remaining flour, salt, and remaining sugar into a large bowl. Make a well in the center.

Add the oil, 1 1/2 cups of lukewarm water, and the yeast mixture to the well.

Mix the dough well with a wooden spoon until a ball forms.

Turn the dough out onto a floured surface and knead for 3 minutes.

Place the dough into a large bowl brushed lightly with oil. Brush the top of the dough with a little oil. Cover and let stand in a warm place for 45 minutes, or until doubled in bulk.

Punch down the dough.

Turn the dough out onto a lightly floured surface and knead for 5 minutes.

Return the dough to the bowl and brush the top with oil. Cover and let stand in a warm place for 35 to 40 minutes, or until doubled in bulk.

Punch the dough down again and turn it out onto a lightly floured surface and knead for 3 minutes.

Preheat the oven to 350°F (175°C). Grease two 9x5-inch loaf pans.

Divide the dough into 4 equal pieces. Knead each piece into a ball.

Place 2 balls side by side into each pan. Let stand in a warm place until the dough reaches the top of the pans, about 25 to 30 minutes.

Brush the top of the bread with the combined egg yolk and 1 tbsp water.

Bake for 40 minutes, or until it sounds hollow when tapped.

Cool in pans for 5 minutes. Remove from pans and cool completely on a wire rack.