Place the bell pepper skin-side up on a medium baking sheet and broil until the skins are well charred all over, 10 to 15 minutes. Transfer the peppers to a small paper bag, seal and leave them to steam for 20 minutes. When done, scrape off the charred skin using the edge of a spoon. Give the peppers a rough chop, then puree them a blender until very smooth. Set aside.
Adjust the oven to 400 degrees F.
Place the sweet potatoes cut-side up in a 9-by-13-inch baking dish. Drizzle with 1/2 teaspoon of the coconut oil and sprinkle with the lime zest and 1/2 teaspoon of the cumin. Bake until fork tender, 30 to 40 minutes.
Meanwhile, combine the chickpeas and water to cover in a small saucepan. Bring to a boil and simmer for 15 minutes. Drain thoroughly and set aside.
Heat the remaining 1 tablespoon coconut oil in a large skillet over medium-low heat. Add the onion and saute 5 minutes. Add the garlic and saute 1 minute more. Stir in the tomatoes and cook for 10 minutes. Add the coriander, the remaining 1 1/2 teaspoons cumin, the red pepper puree and a pinch of cayenne. Cook 1 minute more, then stir in the coconut milk and lime juice. Bring to a low boil, lower the heat and simmer gently for 5 minutes. Stir in the spinach and the drained chickpeas and cook another 3 minutes. Season with salt and pepper.
To serve, arrange a sweet potato half, cut-side up, on a plate. Generously spoon some of the chickpea mixture over the top. Garnish with plenty of shredded coconut, cilantro and green onion. Serve immediately.