French onion soup.  Most likely the most popular
of french dishes eaten at even the most dive diners
in the US.  This dish has been embraced by Americans
because of its meaty agridolce broth and cheesy
topping.

Getting that meaty unctuous broth as
rich and brown as possible without using beef broth
is quite the challenge.  I got around it by enriching
some veg stock with mushrooms roasted with some
tomato paste.  Caramelize a ton of onions and
deglaze twice with apple cider and twice with port wine.
Simmer with stock until soup tastes of sweet onions
and season with salt pepper and a touch of acid.
Ladle into a crock and gratin with gruyere and a
sprinkling of a hard cheese.