Heat oil in a Dutch oven over medium heat. Add onions and cook, stirring often, until fragrant and beginning to brown, 5 to 6 minutes. Add garlic and cook, stirring, until fragrant, about 1 minute. Add cumin seed, ground cumin, coriander, cinnamon, cardamom and cayenne; cook, stirring, until fragrant, 30 to 60 seconds. Add potatoes, water and salt; bring to a simmer. Cover and cook for 10 minutes.

Add chickpeas, tomatoes and carrots; stir to combine. Bring to a simmer. Reduce heat to low and simmer, partially covered, stirring occasionally and adding 1/2 cup water, if needed, until the potatoes and the carrots are tender, 30 to 35 minutes. Stir in cilantro. Serve with yogurt, if desired.