While sweet potatoes are roasting, heat 1 tablespoon oil in a large, heavy-bottomed pot over medium heat. Add onion and garlic; saute until onion starts to soften, about 3-4 minutes. Add chili powder, cumin, chipotle powder, garam masala, and salt. Stir until well-blended. Add tomatoes, 1 1/2 cups Bhakti Chai concentrate, vegetable stock, and raw cacao or cocoa powder. Bring to a simmer. Cover, reduce heat, and simmer for 30 minutes.