Preheat oven to 400°F, toss sweet potato cubes with oil, salt, and pepper. Roast on a baking sheet until edges caramelize, about 25 minutes.

In a large pot over medium heat, warm oil, then add onions, garlic, and ginger. Cook until translucent and fragrant, about 5 minutes.

Stir in cumin seeds, turmeric, coriander, chili powder, and garam masala. Toast until spices bloom, about 1 minute.

Pour in chopped tomatoes, coconut milk, and drained chickpeas. Stir and bring to a gentle simmer over medium-low heat, then simmer for 3 minutes to meld flavors.

Add roasted sweet potatoes to the pot and simmer for 10 more minutes until potatoes are tender and sauce thickens.

Remove from heat, stir in lime juice and cilantro. Adjust salt or spice, then serve hot over rice or with naan.