Prepare the Base Grain: Start by preparing your grain of choice—quinoa, couscous, or bulgur—following the package instructions. Once cooked, fluff with a fork and season lightly with salt. Set aside, covered, to keep warm.
Sauté Aromatics: In a large, heavy-bottomed pot, warm the olive oil over medium heat. Add the diced onion and cook for about 5 minutes, stirring occasionally, until the onion becomes translucent and fragrant. Add the minced garlic and cook for another 1 minute, being careful not to brown it.
Bloom the Spices: Sprinkle in the paprika, cumin, coriander, turmeric, ginger, cinnamon, salt, black pepper, and cayenne. Stir the spices into the onion mixture for 30 to 60 seconds. This step awakens the spices and deepens their flavor.
Add Liquids and Simmer: Pour in the diced tomatoes (with their juices) and the vegetable broth. Stir well, scraping up any bits from the bottom of the pot. Bring the mixture to a low boil.
Simmer with Chickpeas and Sweet Potatoes: Add the sweet potatoes and chickpeas to the pot. Reduce the heat to a gentle simmer, cover, and cook for 25 to 30 minutes, or until the sweet potatoes are fork-tender. Stir occasionally to ensure nothing sticks.
Finish with Greens: In the final 2 minutes of cooking, stir in the spinach. Let it wilt into the stew, preserving its vibrant color and nutrients.
Assemble and Serve: Spoon the stew over your prepared grain. Top each serving with a squeeze of fresh lemon juice, a sprinkle of chopped cilantro, and a generous dollop of Greek yogurt if desired.