In a large bowl whisk together water & yeast, let stand 5 minutes. Whisk in 2 cups of flour to form a thin batter. Cover & refrigerate for 12 hours.
Brush a 9x13 baking pan with oil. Whisk the salt into the batter. Stir in 2.5 cups flour. Knead 5 minutes on floured board, add additional flour to form slightly sticky, but elastic dough.
Roll out to form a rectangle. Transfer into pan, & pat to fill pan. Cover with a towel & let rise at room temperature for 2 hours.
Bake in the upper 1/3 of oven at 400° F for 30 minutes. Remove bread from pan & bake for an additional 5 minutes directly on the oven rack.