The secret to success and the challenge are the same: Time.
Time, not money, is the fundamental ingredient in onion soup. The ingredients couldn’t be more simple: onions, broth, cognac or brandy, some herbs, a crouton and some cheese. But this isn’t a fast food—you need three cups of thinly sliced yellow onions and you need to cook them slowly in butter until they are soft and clear and then further until they are brown and caramelized. This can take 40 minutes or more and you have to watch them so they don’t burn.
After deglazing with a brandy (you can use wine but brandy or cognac deepens the ﬂavor), you stir in stock and really, this should be homemade, too. So back up the whole production a day. You can use boxed beef stock but reduce by ¼ so it will be more intense and drop a bay leaf in it. Without the long-simmered ﬂavors of onions and stock, your soup will be a pallid failure. As it so often is. Season to taste, put the boiling soup into crocks and top with a slice of sturdy French bread which you will have already toasted and top that with plenty of shredded Gruyere. Run it under the broiler or use your propane torch like a champ to brown the cheese. There. Now eat the soup with the same attention it took to make it.
3 cups sliced thinly yellow onions ¼ cup unsalted butter (Some use olive oil; I like butter)
¼ cup white wine or 2-3 Tbsp. Cognac
6 cups strong beef stock
1 bay leaf
salt and pepper 12 slices country French bread or baguette, depending on the size of your crocks 2 cups shredded Gruyere cheese Follow the instructions, left.
(Yes, there are ways to cheat. One of them is called for by none other than Julia. You know, Child.)
Add 2 Tbsp. sugar to the onions when browning
Add 2 Tbsp. balsamic vinegar to browned onions
Add 1-2 Tbsp. Kitchen Bouquet or similar product before final simmer.