The Ultimate: French Onion Soup

***** Petit Robert Bistro

Chef Jacky Robert’s traditional preparation begins with a rich, beefy broth—nicely salted and (this is key) not too sweet, with a hint of white wine. French-bread croutons and caramelized onions, along with a crisp-around-the-edges blanket of Swiss and Muenster cheeses, make this a five-star winner that’s also hearty enough for a meal. Not too shabby for $6.25.

468 Commonwealth Ave., Boston, 617-375-0699; 480 Columbus Ave., Boston,  617-867-0600; 45 Chapel St., Needham, 781-559-0532;

Steam-Tabled [The Runners-Up]:

 ****1/2 The Butcher Shop: Braised oxtail makes for a luxuriously rich (if heavy) broth.
The Butcher Shop, 552 Tremont St., Boston, 617-423-4800,

     **** Aquitaine: Delightful, save for the overbroiled top.
Aquitaine, 569 Tremont St., Boston, 617-424-8577,

    *** Brasserie Jo: Thick, flavorful broth, but too sweet for our tastes.
Brasserie Jo, Colonnade Hotel, 120 Huntington Ave., Boston, 617-425-3240,
** Gaslight: Nice cheesy croutons; watery, underseasoned broth.
Gaslight, 560 Harrison Ave., Boston, 617-422-0224,