Heat oil over medium-high heat in large, heavy bottomed saucepot.
Add the onions and salt, and sauté for 10 minutes or until lightly browned
but not caramelized, stirring frequently.
Add the remaining ingredients. Reduce heat to low and simmer for
40 minutes, stirring occasionally. As the liquid evaporates, you should be
left with well cooked, but identifiable, slices of onion in a thick sauce.