Step 1
Wrap one 10-oz. package deal frozen chopped spinach, thawed, in a clear kitchen towel and twist and squeeze towel tightly over the sink to expel as a lot liquid as attainable.
Step 2
Soften 2 Tbsp. unsalted butter in a medium Dutch oven or different heavy pot over medium-high warmth. Add spinach and ½ cup finely chopped herbs (similar to cilantro, parsley, and/or dill) and season with kosher salt. Prepare dinner, stirring sometimes and breaking apart spinach, till combination is mixed and spinach and herbs are barely darkened in shade, about 4 minutes. Switch to a bowl.
Step 3
Warmth 3 Tbsp. extra-virgin olive oil in similar pot over medium-high. Add 3 medium onions, thinly sliced, and season with salt. Prepare dinner, stirring sometimes, till flippantly browned and frizzled across the edges, 9–12 minutes. Add 5 garlic cloves, thinly sliced, and cook dinner, stirring typically, till softened and aromatic, about 1 minute. Add 1 Tbsp. floor coriander, 2 tsp. floor cumin, ½ tsp. crushed crimson pepper flakes, and a few grinds of freshly floor black pepper. Prepare dinner, stirring typically, till mixed, about 1 minute.
Step 4
Add ⅔ cup basmati rice, ⅔ cup French inexperienced lentils, 4 cups low-sodium vegetable broth, 2 tsp. Diamond Crystal or 1¼ tsp. Morton kosher salt, and 6 cups water; stir to mix. Enhance warmth to excessive and convey soup to a boil. Cut back warmth so soup is at a simmer and cook dinner till rice is cooked via and lentils are tender (they are going to nonetheless retain a little bit of chunk), 30–35 minutes.
Step 5
Stir spinach combination into soup and cook dinner, stirring typically, till mixed and heated via, about 3 minutes. Take away pot from warmth and add juice of 1 lemon and remaining 2 Tbsp. unsalted butter; stir till butter is melted. Style soup and season with salt and black pepper.
Step 6
Combine 1 cup plain whole-milk yogurt, a massive pinch of salt, and remaining 2 Tbsp. extra-virgin olive oil in a small bowl to mix. Ladle soup into bowls and high every with a spoonful of yogurt combination to serve.
