Thoroughly pick over and rinse the chana dal, then set aside for later.
Heat a dry pan over medium heat. Add the gram flour and toast until golden. Watch not to burn. Transfer the gram flour to a bowl and whisk with ½ cup of water. Set aside.
Heat 2 tablespoons vegetable oil in a pan over medium-high heat. Once hot add the cumin seeds, mustard seeds and dried chillies. Cook until the seeds begin to pop, around 30 seconds.
Add the shallot and cook until they are beginning to turn golden, around 5 minutes.
Add the garlic and continue to cook for 1 minute.
Next, add the spices and cook for a further 1 minute. Turmeric, garam masala, Kashmir chilli powder, ground coriander and cracked black pepper.
Now add the chana dal, 1 litre vegetable stock, 1 tablespoon tamarind paste and the reserved toasted gram flour mixture.
Bring to a boil for 10 minutes then turn down the heat to a gentle simmer. Simmer for a further 30 minutes. Check that the chana dal is fully cooked, if they require more time then continue to cook until ready.
Taste for seasoning and add salt. The amount needed will depend on how salty the vegetable stock is.
Serve the soup with samosas and finely sliced vegetables. Squeeze over a wedge of lime before eating.