This is the best French Onion Soup I have ever had and maybe it is because of the twist - using Mexican Oaxaca cheese!
(Queso Oaxaca or Quesillo Oaxaca is a white, semi-hard cheese from Mexico, similar to unaged Monterey Jack but with a mozzarella-like string cheese texture. It is named after the state of Oaxaca in southern Mexico, where it was first made. It is available in several different shapes. It is also known as quesillo Oaxaca or thread cheese when shaped like a ball. Shaped in bricks for slicing, it is called asadero (meaning "roaster" or "broiler") or queso quesadilla.)
2 pounds medium onions, halved lengthwise, then thinly sliced lengthwise
3 sprigs fresh thyme
2 Turkish bay leaves or 1 California
3/4 teaspoon salt
1/2 stick unsalted butter
2 teaspoons all-purpose flour
3/4 cup dry white wine
4 cups reduced-sodium beef broth (32 fl oz)
1 1/2 cups water
1/2 teaspoon black pepper
6 (1/2-inch-thick) diagonal slices of baguette
1 (1/2-lb) piece Oaxaca Cheese
Cook onions, thyme, bay leaves, and salt in butter in a 4- to 5-quart heavy pot over medium-low heat, uncovered, stirring frequently, until onions are very soft and deep golden brown, about 45 minutes.
Add flour and cook, stirring, 1 minute.
Stir in wine and cook, stirring, 2 minutes.
Stir in broth, water, and pepper and simmer, uncovered, stirring occasionally, 30 minutes.
While soup simmers, put oven rack in middle position and preheat oven to 350°F.
Arrange bread in 1 layer on a large baking sheet and toast, turning over once, until completely dry, about 15 minutes.
Remove croûtes from oven and preheat broiler.
Put crocks in a shallow baking pan.
Discard bay leaves and thyme from soup and divide soup among crocks, then float a croûte in each.
Slice enough Oaxaca Cheese (about 6 ounces total) with cheese plane to cover tops of crocks, allowing ends of cheese to hang over rims of crocks, then sprinkle with Parmigiano-Reggiano.
Broil 4 to 5 inches from heat until cheese is melted and bubbly, 1 to 2 minutes.
Special equipment: 6 (8- to 10-oz) flameproof soup crocks or ramekins; a cheese plane