French Onion Open Faced Sandwich has all the flavor and umami of the traditional soup, but in sandwich form.
This is the sandwich that will convince you, if you still need convincing, that sandwiches can be dinner. The onions slow-cook to a deep, burnished hue, with all the nutty sweetness that comes with caramelized onions. They’re sparked with thyme from the garden, garlic, a little tang from balsamic vinegar and some butter and brown sugar, just because it’s the right thing to do.
Once the onions are cooked, it’s a 5-minute job to layer things onto some sourdough bread and heat it all up so the cheese melts. Melty cheese, caramelized onions, and a chew from good sourdough bread are basically what you need, what you want, and what this deeply satisfying meal delivers. Asked for and answered!
How to make a French Onion Open Faced Sandwich
First, gather all of the ingredients to make the onions. We’ll do them in the slow cooker and they cook for 10 hours, so you can do the onions a day or more before you intend to eat the sandwich. We’ll need:
- vidalia onions
- fresh thyme
- garlic
- brown sugar
- butter
- balsamic vinegar
- salt
- pepper
Put the sliced onions in the slow cooker. Do you like my vintage cooker? My mom gave it to me in 1974. Check the periwinkle blue.
Add the other onion mixture ingredients to the pot (no need to stir; it will all come together as it cooks). Can you see all the different things (the little cubes are cut-up butter)? Put the lid on and let it rip overnight.
When you’re ready to assemble your sandwiches, gather your ingredients. We’re using:
- Dijon mustard
- sourdough bread
- scallions (green onions)
- Gruyere cheese
- fresh thyme
- fresh chives (if you have them in the garden, and chive flowers if it is that season!)
When the onions are done, they should be a deep brown color, which will bring out lots of flavor and natural sweetness.
I usually use a tongs to lift them from the crock.
To assemble the open faced sandwich, spread the bread with Dijon mustard.
Pile on the onions and cheese.
Fling some chopped scallions on top, along with some fresh thyme, and heat it. I decided to use the air fryer instead of the big oven because I didn’t want to heat up the kitchen.
It isn’t hard to make your sandwich look as pretty as the one in the book!
Just layer neatly and garnish! You get a lot of garnish-power from chive flowers, if you have them on your chive plant.
How did I do?
Where does this recipe for French Onion Open Faced Sandwich come from?
This recipe is from “The Happy Sandwich: Scrumptious Sandwiches to Make You Smile [1],” {affiliate link} by Jason Goldstein (2021; Famlius publishing). Jason is a chiropractor by day, but perhaps is more widely known from Chop Happy, his food blog. He likes to showcase rich flavors and easy comfort food; this sandwich book is a good example of his inventive approach to delicious meals. He has slow cooker, sheet pan, no-cook and no-bread sandwich chapters, and an entire section devoted to grilled cheese (obviously!). We both agree that sandwiches can be for any and every meal! This would make a great gift book for young adults especially, or cooks of all ages who enjoy an unusual sandwich.
Ready to make this sandwich? Let’s go!
French Onion Open Faced Sandwich has all the flavor and umami of the traditional soup, but in sandwich form. This is the sandwich that will convince you that sandwiches can be dinner.
Ingredients
- For the onions
- 3 pounds vidalia onions, sliced
- 1 tablespoon fresh thyme, chopped
- 2 cloves garlic, pressed or crushed
- 2 tablespoon brown sugar
- 2 tablespoons butter
- 1 teaspoon balsamic vinegar
- 1/4 teaspoon kosher salt (Diamond Crystal brand used)
- Freshly ground black pepper
- .
- For the sandwich assembly
- 4 tablespoons Dijon mustard
- 4 slices sourdough bread
- 3 scallions, chopped
- 2 cups (about 8 ounces) grated gruyere cheese
- 2 teaspoons fresh thyme, chopped
- Snipped fresh chives, for garnish, if you like
Directions
- Place onions, thyme, garlic, brown sugar, butter, balsamic vinegar, salt and pepper in the crock of a slow cooker. Cover and cook on low for 10 hours. (I did mine overnight, and once I woke up and saw them I wanted them more brown, so I cranked it up to high for a couple of additional hours the next morning. Slow cookers vary (mine is 40+ years old), so your mileage may vary.)
- Once the onions are cooked, heat the oven to 500F degrees.
- Spread Dijon mustard on each slice of sourdough bread and place the bread on a sheet tray.
- Place a heaping mount of onions onto each slice of bread. Top with scallions, cheese and a sprinkling of thyme. Place on the top rack of the oven for a minute or two until the cheese melts. Remove from oven and sprinkle with snipped chives, if you're using (for colorful garnish).
- NOTE: I heated my open-faced sandwiches in my air fryer (400F degrees for about 5-8 minutes) because I didn't want to heat up the whole kitchen. Use the method that works for you!
- Serve on a place with a knife and fork.
- Serves 4.
Notes
Recipe source: "The Happy Sandwich: Scrumptious Sandwiches to Make You Smile," by Jason Goldstein (2021, Familius; $19.99)
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