1/4 cup shredded Gruyère or other aged Swiss cheese (1 ounce)
Heat the oil in a nonstick stockpot or extra-large saucepan over medium heat. Add the onions, vinegar, and 1/8 teaspoon of the salt and cook while stirring occasionally until softened, about 10 minutes. Increase heat to medium-high, add the mushrooms, and sauté until the onions are well caramelized, about 15 minutes. Add the broth, the remaining 1/2 teaspoon salt, the pepper, rosemary, and the chopped thyme and bring to a boil over high heat. Reduce heat to low, cover, and simmer until the flavors are developed, about 10 minutes. Meanwhile, preheat the oven to 500°.
Place 5 ovenproof soup bowls or crocks onto a baking sheet. Adjust seasoning and ladle the soup into each bowl. Place two of the pita chips on top of each and sprinkle with the cheese. Bake in the oven on the top oven rack until the cheese is bubbly, about 4 minutes.
Garnish each with a thyme sprig, and serve.
Recipe adapted with permission from The With or Without Meat Cookbook by Jackie Newgent, RDN, CDN (American Diabetes Association, 2014)