Fry the onions: Set a large dutch oven over medium-low heat with ⅓ cup extra-virgin olive oil and 2 large yellow onions, thinly sliced. Give them a big pinch of salt and pepper.Cover and cook for 10 minutes, stirring halfway, until the onions soften and start to color. Uncover and saute over medium heat for another 15 - 25 minutes, stirring occasionally, until the onions are deeply browned and shriveled. Aim for a mix of golden, browned, and slightly crispy strands. Transfer half of the onions to a small bowl, give them a pinch of salt, and set aside.Note: Don't rush cooking the onions here. They are driving the flavor of the soup!
Add the spices: Stir in 2 teaspoons ground cumin, 1 teaspoon ground coriander and a pinch of cinnamon.
Simmer: Add ¾ cup dried brown lentils, ¾ cup pearl barley, and 8 cups of broth.Cover and bring to a boil, then uncover and reduce the heat to medium-low. Simmer until the lentils and barley are cooked through, 35 - 40 minutes. If needed, stir in the remaining broth to loosen the soup to your desired consistency. Then, taste and adjust the soup for seasonings. Note: If you're using low-sodium broth, make sure to add another big pinch of salt here.
Prepare the mint yogurt: Meanwhile, preparing the yogurt topping. In a small bowl, combine 1 cup plain full-fat Greek yogurt, 1 clove garlic, and 1 ½ teaspoons dried mint, and the zest of 1 small lemon to the yogurt. Season with salt to taste. Keep chilled in the fridge while the soup cooks.
Serve: Divide amongst serving bowls, and top each with a big dollop of mint yogurt, the browned onions, a pinch of Aleppo pepper, ¼ cup fresh parsley, and warm pita (if desired).
Notes
* I use half the amount of bouillon paste to control salt levels. So, for 8 cups of water, I use about 4 teaspoons bouillon.Storage: This soup is a great option for meal prep as long as all of the components are kept in separate, airtight containers in the fridge. * The soup should last about 4 - 5 days in the fridge. Reheat in the microwave or on the stove until warm. * The onions and parsley will also last about 4 - 5 days. * The mint yogurt will last about 2 - 3 days. For a longer shelf-life, replace the raw garlic with ½ teaspoon garlic powder.