Sweet Potato Chana Masala

Name: Sweet Potato Chana Masala
Ingredients: 1 cup diced sweet potato (one medium large); 1 tablespoon clarified butter or grapeseed oil; 1 cup diced onion; 1 minced garlic clove; 1 teaspoon coriander seed; 1/2 teaspoon cumin; 1/2 teaspoon cardamom; 1-1/2 teaspoon garam masala; 1/2 teaspoon grated fresh ginger; 1 serrano chile, seeded and minced (to taste, an entire chile is spicy); 1 teaspoon salt; 1 can garbanzo beans (15 oz), drained and rinsed; 1 pint crushed tomatoes; 1/4 cup rough chopped cilantro; 1/3 cup Greek yogurt, full fat