It's worth the effort to make your own stock for this supersimple soup, but if you want to save time, you can use store-bought lower-sodium broth. You'll need to reduce the amount of salt you add to the soup by half.
To prepare stock, arrange first 5 ingredients in a single layer on a large baking sheet. Bake at 450° for 35 minutes or until browned. Scrape beef mixture and pan drippings into a large Dutch oven. Stir in 3 quarts cold water and next 4 ingredients (through bay leaf); bring to a boil over medium heat. Reduce heat to low, and simmer 2 1/2 hours, skimming surface as necessary. Strain mixture through a fine-mesh sieve lined with a double layer of cheesecloth over a bowl; discard solids. Wipe pan clean with paper towels.
To prepare soup, return Dutch oven to medium heat. Add oil to pan; swirl to coat. Melt butter in oil. Add sliced onion to pan; cook for 5 minutes, stirring occasionally. Partially cover, reduce heat to medium-low, and cook 15 minutes, stirring occasionally. Add salt and ground pepper; cook, uncovered, until deep golden brown (about 35 minutes), stirring frequently. Add reserved stock and chopped thyme; bring to a boil. Reduce heat, and simmer until reduced to 8 cups (about 50 minutes). Stir in chives.
Preheat broiler to high.
Arrange bread slices in a single layer on a jelly-roll pan, and broil for 2 minutes or until toasted, turning after 1 minute. Ladle 1 1/3 cups soup into each of 6 broiler-safe soup bowls. Top each serving with 2 bread slices, and sprinkle evenly with cheese. Place soup bowls on jelly-roll pan, and broil for 4 minutes or until tops are golden brown and cheese bubbles.
This is a pretty spot-on recipe, and close to the way I’ve
been making it for decades. However, if you want to kick this up a notch, try
serving the soup in bread bowls. Just remember, that after you pull much of the
dough out of the center of the bread, to coat the inside with olive oil and
toast the inside of the bowl.
BTW, grated baby Swiss works as well and tastes almost as
good as Gruyere; and you don’t have to take out a home equity loan to afford it.
This is a real winner. It's sooo good! I did use a purchased reduced beef stock & it still TOOK SOME TIME!. My daughter & I freaked out over the amount of onions it took, but they reduced A LOT!. We dine regularly at an exquisite French restaurant in Coconut Grove, & 3 out of 3 of us, thought this recipe was better than the restaurant's! I'm super happy with this recipe!