In a large sauté pan or Dutch oven over medium heat, add ghee. When hot, add onions and season with salt; sauté for 2 minutes. Add red peppers and sauté for 2 minutes.
Add garlic, ginger, cinnamon stick, cardamom pods, curry powder, cumin, garam masala and fennel seeds; sauté for 2 minutes.
Add tomato paste and stir to coat.
Add chicken cubes and season with freshly ground black pepper. Cook until no longer pink, about 5 minutes, stirring often.
Add diced tomatoes, brown sugar and potato cubes; stir well. And broth enough to just cover everything. Stir well, bring to a boil before reducing back to medium. Simmer for 25 minutes or until potatoes are tender.
Meanwhile, cut the tops off buns and scoop out the inside to create a bowl; set them aside.
After 25 minutes, add chickpeas and lime juice. Mix well and cook for an additional 10 minutes.
When curry is cooked, remove the cinnamon stick and discard it. Remove the sauté pan from the heat and let the mixture rest for 10 minutes.
Spoon curry into the prepared buns, sprinkle on cilantro and serve with lime wedges.