Today, we have a special surprise! This is our first guest post by a great friend from graduate school. The recipe looks amazing and I can't wait to try it out. Hope you guys enjoy!

This recipe comes from Cook's Illustrated All-Time Best French Recipes. Here’s a tip: go to your local library and look for Cook’s Illustrated cookbooks or America’s Test Kitchen DVDs. I like these recipes because they are generally straightforward in terms of ingredients and cooking techniques. However, if a recipe calls for it, one thing they don’t skimp on is TIME.

Time is the secret to today’s recipe: French Onion Soup. There will, of course, be thyme--but the real secret is time.

Supplies

This recipe can be broken into three stages, so I think it’s helpful to break out the equipment and ingredient list into those three stages as well.

Stage 1: Prep and Oven

Equipment: oven; cast-iron Dutch oven (7 quarts or larger); cutting board; chef’s knife; mandolin (optional); sturdy wooden or high-heat resistant silicone spoon/spatula; measuring spoon;

Ingredients: yellow onions (4 pounds); unsalted butter (3 tablespoons); salt (1 teaspoon); cooking spray;

Stage 2: Stove-top

Additional Equipment: stove-top or burner; measuring cups;

Ingredients: dry cooking sherry (½ cup); beef broth (2 cups); chicken broth (4 cups); fresh thyme (6 sprigs); bay leaf (1 leaf); water (end up using about 3 cups total); salt;

Stage 3: Garnish and Serve

Additional Equipment: oven or broiler; baking sheet; bread knife; cheese grater; oven-safe bowls

Ingredients: baguette; Gruyere cheese, shredded (about 2 cups); salt and pepper; dried thyme or tarragon (optional)

Cooking

We’ll keep a check on time throughout the recipe, so that we can see how long it really takes.

Time-check: 1:05pm

Stage 1: Prep and Oven

Preheat oven

Adjust oven rack to lower position, such that Dutch oven can be placed in center of oven. Preheat oven to 400 F.

Prep onions

Peel and slice 4 pounds onions. Yes, that is a lot of onions! Don’t be alarmed, they will reduce in volume significantly during the cooking process.

What kind of onions to use?

Yellow onions are the winner here. White onions don’t have enough flavor, while Mayan sweet onions are too sweet for this savory application. Red onions would just be kind of weird in French onion soup.

Slicing the onions

How vegetables are sliced affects how they break down during the cooking process. Because this recipe has such a long cooking time, it is very important to slice the onions in the right way. To help peel the onions, I sliced them in half. Notice that I sliced through the root end, or with the grain. This is important.

To slice the onions for this soup, you want to slice with the grain, or “north-south” through the root. If you’re still unsure, you can think about this as opposite of the way you’d slice onions for onion rings.

To help slice 4 pounds of onions, I recommend a mandolin--and don’t forget the safety guard or safely glove when using a mandolin!

Season the onions

Liberally coat the inside walls and bottom of the Dutch oven with cooking spray or vegetable spray. Load all the sliced onions into the pot. Cut 3 tablespoons butter into a few chunks and place on top of onions. Sprinkle over 1 teaspoon salt. Don’t worry if the pot is loaded all the way to the top; that will be fine!

Oven cooking stages

The onions will now cook in the oven in three sub-stages. Time check: 2:04pm.

Place pot in oven with lid secured. Cook for 1 hour.

After 1 hour, the onions will start to wilt and release their moisture. Stir the onions, making sure to scrape the browned bits off the sides and bottom of the pot.

Replace pot in oven with the lid slightly ajar. This will let the moisture cook off in the oven. Cook for 1 hour more.

Remove the pot and stir and scrape the onions again. At this point, they will still be translucent, but starting to brown. Replace the pot in the oven with the lid ajar. Cook for about 35-45 minutes more.

Time check: 4:37pm. Remove the pot from the oven. The onions will have reduced significantly in volume compared to their raw starting point. They should be lightly browned.

(Note: you can leave the oven on)

Stage 2: Stove-top

Transfer the Dutch oven to the stove-top. The secret to this stage is multiple de-glazing. This is where the rich flavor comes from, so please don’t rush any steps on the stove-top!

After the oven stage, the onions will still have some moisture in them. First cook the onions over medium/medium-high heat until they get nice and golden. Keep scraping the bottom and sides of the pot so that the onions don’t stick. After about 15-20 minutes the onions will be dark golden brown and paste-like. Adjust heat as necessary to prevent onions from burning. Time check: 4:53pm

De-glaze

De-glazing is a general technique for re-dissolving food residue. In this recipe, we de-glaze a total of 4 times, which is many more than most recipes call for.

After the initial 15-20 minute cook on the stove-top, you can then let a brown crust start to form on the bottom of the pot. You still want to actively stir the mixture, but don’t scrape so hard as to prevent that crust from forming.

When you get a nice dark crust, but before the bottom of the pan starts to burn, it’s time to de-glaze. Pour ¼ cup water into the pot and use that liquid to scrape the bottom of the pot and re-dissolve the browned bits. In between de-glazings, stir the mixture and allow all the liquid to cook off.

De-glaze 2 more times with ¼ cup water each.

De-glaze a 4th time with ½ cup dry sherry.

Time check: 5:19pm

Simmer

After all the liquid is cooked off from the sherry de-glaze, add beef broth (2 cups), chicken broth (4 cups), and 2 cups water. Scrape the bottom and sides of the pot well.

Toss in 6 sprigs fresh thyme (I have some lovely fresh thyme growing on my kitchen porch!), one bay leaf, and a sprinkle of salt (½ teaspoon).

Bring to a boil, and then reduce to a slow simmer. Cover and let simmer for 30 minutes.

Time check: 5:29pm

Stage 3: Garnish and Serve

While the soup is simmering, you now have time to prepare the garnish.

Slice the baguette and place in the oven to toast. Toast until very lightly golden brown. You can leave the oven on after the onion oven cooking stage and use the hot oven to toast the bread.

Grate the Gruyere cheese. I decided to use a mix of medium (aged 5 months) and intense (aged 12 months) Gruyere. I really like strong cheeses, but you can use a mild Gruyere if you prefer.

Now move the oven rack to the top position, and turn the broiler to High.

After the soup simmers on the stove for about 30 minutes, fish out the thyme sprigs and bay leaf, and season with salt and pepper to taste. Note, you should not need much more salt. In fact, if you feel the broth has reduced a little too much to your taste, you can even add a bit of water.

Ladle the soup into oven-safe bowls. Place bowls on baking sheet for ease in getting them in and out of the broiler.

Float the baguette toasts on top (do not overlap), and cover lightly with cheese. This recipe is all about the rich onion flavor, so you actually don’t want a thick cheese crust. Just use a moderate sprinkle of cheese.

Place sheet with bowls right under the broiler for just a few seconds--just long enough for the cheese to fully melt.

Garnish with fresh cracked black pepper and (optionally) a little dried thyme and/or tarragon.

Time check: 6:04pm. Bon appétit!

Epilogue

So was all that time really worth it? Yes, I think so. If you like French onion soup, you owe it to yourself to try out this recipe!

Don’t have a 5-hour chunk of time? You can actually make this soup over multiple days. After the oven stage, let the pot cool down and refrigerate the oven-roasted onions for up to 3 days. Pick the recipe back up at the stove-top stage.

Alternatively, you can let the soup cool after the stove-top simmer, and refrigerate for up to 2 days. When ready to eat, warm the soup to a simmer on the stove (likely need to add a bit of water to the broth and adjust salt and pepper seasoning), prepare the toast and cheese garnish, and serve.