3cupsloosely-packed fresh baby spinach leaves(or more, if you like - up to 6 ounces)
(optional) fresh lemon juice, for serving
Warm the oil in a large pot. Add the onion and a pinch of salt, and saute until translucent, stirring occasionally; 3-5 minutes.
Add the garlic, ginger, and fresh turmeric (if using), stir, and cook for another about 60 seconds or until softened and fragrant.
Stir in the carrot, ground turmeric (if using), ground cumin, and ground coriander. Cook for 2-3 minutes more, stirring occasionally, until the spices are fragrant and the carrot softened slightly.
Add the vegetable broth, red lentils, and pearl barley to the pot. Bring to a boil, then reduce to a simmer. Cook uncovered for about 20 minutes, or until the lentils and barley are both cooked through.
Stir in the tomato paste, and season to taste with salt and pepper.
Stir in the spinach, turn off the heat and cover the pot with a lid. Remove after 2-3 minutes, or when the spinach is wilted to your preference.
Serve hot, with a light squeeze of fresh lemon juice if desired.
Seriously, do a really good job of rinsing the barley. I rinse mine by putting it in a bowl, filling the bowl with hot water, using my hands to agitate the barley and loosen the starches on the exterior, tipping out most of the water, and repeating this process 4 or 5 times. If you don't rinse well, you could end up with slimy barley and/or a glue-like consistency to your soup. Nobody wants that.