These vegan French onion burgers are made with savory caramelized onion and lentil patties, topped with an extra layer of caramelized onions and creamy herbed cashew cheese.
I didn't actually go into this one intending to turn French onion soup into a burger — it was more of a loose idea to put caramelized onions into a burger. Once I got rolling though I realized it had to be French onion soup, because duh, French onion soup is fantastic.
It's also something that I really miss from time to time, and as my husband and I discovered while chatting one day, lots of new vegetarians are apt to eat by mistake before realizing it's totally not vegetarian. So I think lots of us probably have a good deal of attachment to French onion soup. It's obviously not vegan, so no more goofing up in that department.
So maybe some day I'll make a vegan French onion soup that's actually a soup, but for now...burgers!
Lentil patties seemed appropriate, so I went with that and added some savory seasonings.
Then I topped everything with a creamy herbed cashew cheese. You could use some homemade or store-bought vegan mozzarella if you're a real stickler when it comes to French onion soup-themed things, but honestly, the spreadable cheese is delicious and it really does taste French onioney when paired up with the burger and caramelized onions, so you should make it.
My only regret was going with regular old burger buns. How perfect and delicious would these have been on crusty French rolls? Kind of like the croutons in French onion soup, right? But by the time I figured that out I'd photographed and devoured my burgers, so too late. But maybe some nice person will try out the crusty bread variation and let me know how great it is. :)
Vegan French Onion Burgers with Herbed Cashew Cheese
For the Patties and Caramelized Onion Topping
- 2 tablespoons olive oil plus a little extra for grilling the patties
- 1 ½ pounds yellow onions about 3 medium, sliced thin
- 3 garlic cloves minced
- 1 ¼ cup rolled oats
- 2 cups cooked brown lentils see note
- ½ cup chopped walnuts
- 2 tablespoons chopped fresh parsley
- 1 tablespoon fresh thyme leaves
- 2 tablespoons soy sauce
- 1 tablespoon vegan Worcestershire sauce
- ½ teaspoon black pepper
For the Herbed Cashew Cheese
- 1 cup raw cashews soaked in water 4-8 hours, drained and rinsed
- 1 tablespoon red wine vinegar
- 1 garlic clove minced
- ¼ cup unflavored unsweetened soy or almond milk
- ½ teaspoon salt
- ¼ cup chopped fresh parsley
- 2 tablespoons fresh thyme leaves
- 2 tablespoons chopped fresh chives
- 4-6 burger buns or crusty French rolls
- Lettuce tomato, and any other burger toppings of your choice
Coat the bottom of a large skillet with olive oil and place it over medium-low heat. Add the onion and stir a few times to coat with the oil. Allow to cook for 45 minutes to 1 hour, stirring occasionally, until the onions are browned and caramelized. Stir in the garlic, raise heat to medium, and cook for another minute, until very fragrant. Remove from heat and transfer the onions to a plate.
Place the oats into the bowl of a food processor and blend to a flour. Add in the lentils, walnuts, parsley, thyme, soy sauce, Worcestershire sauce, black pepper, and about ⅔ of the caramelized onions. Pulse until the ingredients are well mixed, being careful not to overdo it. Taste-test and adjust the seasonings to your liking.
Make the cashew cheese by placing the cashews, garlic, red wine vinegar, milk, and salt into the bowl of a food processor and blending until smooth. Add in the herbs and pulse a few times until finely chopped and well mixed. Scoop the mixture into a bowl.
To make the burgers, shape the lentil mixture into 4 to 6 patties. Add a touch more oil to the skillet you used for the onions and place it over medium heat. When the oil is hot, add the patties and cook for about 4 minutes on each side, until browned.
Stuff the patties into buns or rolls and top with the cashew cheese, remaining caramelized onions, and any other toppings you like. Serve.
You can use canned lentils, or cook up some dried lentils while the onions caramelize. If using dried, place ¾ cup into a saucepan and cover with about 3 cups of water. Boil until the lentils are tender, about 35 minutes, then remove from heat and drain any excess water. If you forget to soak your cashews, you can just boil them in water for about 15 minutes.