Soak Channa overnight, (at least for 6 hours) in water. Pressure cook it along with Potatoes, to get tender channa dal. Ensure its not soggy.
Cut Onions, Tomatoes into pieces. Add fresh Ginger, Garlic and make everything into fine paste.
Heat Oil in a kadai, put the masala paste. Sauté on high flame. Add all the powders. Cook for 5 mins.
Then, add the cooked Channa to the kadai. Mash all the potatoes and add to the gravy to get thick consistency. Sim it for a while until you get a thick gravy.
You can add the potatoes as cubes, also but mashed potatoes make gravy thick. If you want to add it as cubes, then pressure cook Channa and keep it for 2 whistles, then add potatoes and again put on whistle for 2 more. I thick everybody mostly pressure cooks channa otherwise it takes lot of cooking time.
Finally garnish it with Coriander leaves, Onion and Lime pieces.