It will take a while to caramelize the onions for the base of this soup, but the result is a deeply flavored dish that will warm your soul. Beef broth is also an essential part of the recipe. If you’re using store-bought broth, as I do here, please taste it before using it to see if you like it. If you want to enhance the flavor, simmer it with the ends and peels of the onions for about 20 minutes, and then strain it. The onions are deglazed with dry white wine or sherry, and the soup is often served with a splash of brandy. You can omit the alcohol; the flavor will be just slightly less intense. I have served French onion soup in many variations, depending on the occasion: individual tureens, larger soufflé dishes to serve a larger group, and even rectangular casserole dishes, lasagna-style. However you make …