Total time: 1½ hours
Note: Adapted from Michael Ruhlman's "Ruhlman's Twenty."
1/4 cup (½ stick) butter, divided
1 onion, sliced
1 shallot, roughly chopped
3 tablespoons flour
1 1/2 cups milk
1 tablespoon white wine vinegar
3 tablespoons sherry
1 tablespoon fish sauce
1 to 2 teaspoons dry mustard
1/4 teaspoon freshly ground black pepper
6 or 7 gratings of fresh nutmeg
1/4 teaspoon cayenne or smoked paprika
1. Melt half the butter in a medium pan over medium heat and add the onion and a four-fingered pinch (about one-fourth teaspoon) of salt. Cook, stirring until the onion is nicely caramelized, about 20 minutes.