Soak the channa dal for 2 hours, or longer. Drain water and rinse well.
Cook the chana dal: You can cook the channa dal in a pressure cooker or a regular saucepan. Combine channa dal with cold water and a pinch of salt. The pressure cooker needs 2 cups water and 10 minutes under high pressure. The saucepan will need 3 cups water and about 40 minutes to simmer. The dal is cooked when it is soft and starting to fall apart.
Finish the chana dal: Heat a medium saucepan on medium-low heat and add oil and black mustard seeds. When about half of the mustard seeds have popped, add the optional asafetida and turmeric powder and sizzle for about 20 seconds. Then immediately add the cooked channa dal (along with the cooking water) and ½ teaspoon of salt. Stir, and mash slightly with your spoon. Simmer for 8–10 minutes.
Method for the potato patties
Wash 3-4 potatoes (2 cups worth) and place in a saucepan. Cover with cold water by 2 inches, then place on high heat and bring to a boil. Turn down to a simmer and cook for 15-20 minutes, partially covered, until a knife inserted into the potato comes out easily. Drain the water and set aside the potatoes to cool.
Use your hands to crumble the potatoes as finely as possible, or a potato masher to mash the potatoes (or both).
In a medium bowl, combine the mashed potatoes, rice flour, turmeric powder, red chili powder, garlic, ginger, green chili, and salt. Mix well.
Roughly divide the potato mixture into 8 equal portions using a knife. Roll the first portion into a ball using your hands, then smush slightly so it looks more like a thick disk. Set on a plate or cutting board, then repeat with the remaining portions.
Place a sauté pan on medium-low heat. Add half the ghee. Place the potato patties in the pan and fry until golden brown. Turn the patties over and add the rest of the ghee. Cook until both sides are golden brown. (If you like, sprinkle on extra spices before turning them the first time.)
To serve
Place a quarter of the hot dal on a plate or in a wide bowl. Top with two potato patties.
Garnish with minced red onion, finely chopped tomato, and/or coriander leaves. If you have the chutneys, you can spoon some on top of the patties just before serving.