Toast the coriander seeds and cumin seeds in a pan on a medium heat until fragrant.
Using a pestle and mortar, bash up the cumin seeds and coriander seeds until fine.
Add the cumin and coriander powder to a bowl with the turmeric, chilli powder, garam masala followed by a pinch of salt and pepper and set aside.
Using a pestle a mortar, bash up the garlic and ginger with a pinch of salt until a paste and set aside.
Put a medium-sized pan on a medium heat, add a touch of vegetable oil followed by the red onion, red chilli, garlic and ginger paste and cook until the onion starts to turn tranclucent.
Add the dry spices, stir well and cook until the spices are fragrant (don’t burn the spices!)
Add a knob of butter and stir in the tomato purée. Cook for a few more minutes then spoon the spice mixture into a bowl and set aside.
Using the same pan, add the lentils and the chicken stock with a knob of butter then stir well, ensuring you pick up any remaining spices that have stuck to the bottom of the pan. Add enough cold water to come to around two inches above the surface.
Bring to the boil then reduce to a gentle simmer and cook for 10 minutes until the lentils are soft.
Stir in the spice mixture and cook for a further 5 minutes or so.
Add more water depending on your desired consistency then add the coriander to serve!
An unstructured digest of stuff that I've found on the information superhighway.