In a large pot or Dutch oven, heat coconut oil over medium heat. Add diced onion and cook until softened, about 5 minutes. Stir in garlic and ginger, cooking for 1 minute until fragrant.
Add curry powder, cumin, turmeric, and cayenne (if using). Stir constantly for 30 seconds to toast the spices and release their aroma.
Add cubed sweet potatoes, chickpeas, coconut milk, and vegetable broth. Stir to combine. Bring to a boil, then reduce heat to low, cover, and simmer for 20-25 minutes until sweet potatoes are tender.
Remove from heat. Stir in lime juice and season with salt and pepper to taste. Adjust spices if desired.
Spoon rice into bowls and top with curry. Garnish with fresh cilantro. Serve hot.