I've refined this curry over a couple of years and it has its roots in a sort of Bengali Masala
I make no claim as to authenticity, but if you give it a go, I sincerely believe you will not be disappointed. The ingredient list seems large, but all spices should be available from any Asian shop (or even decent supermarket - I've given the Asian names where I know them). All quantities are approximate and are expressed UK style (tsp = teaspoon etc), however in practice quantities aren't critical (I just measure stuff out onto the palm of my hand).

Serves 2 (proper portions:-)
Preperation time ~ 45 mins

1/2 tsp black mustard seeds
1/2 tsp black onion seeds (Kalonji)
4 Cardamom pods
4 Cloves
1 tsp Fennel seeds
4-10 dried birds eye chillies (pick your heat:-)
1 tsp Coriander seeds (Dhaniya)
1 tsp Cumin seeds (Jeera)
1 1" piece Cassia bark (or Cinnamon)
1/2 tsp Turmeric
1/2 tsp Ginger powder
1 medium onion chopped fine
2 cloves garlic chopped fine
1 sweet red pepper, cut into chunks
2 tablespoons full fat natural yoghurt (low fat will probably split)
2 tsp tomato paste
2 chicken breasts cut into chunks (or other meat / veg if preferred - works well with most stuff)
Vegetable oil

Heat about 2 tablespoons oil in a large heavy frying pan over a moderate heat. When hot, place the mustard seeds and onion seeds into the hot oil. As soon as the seeds start to pop and spit add the onion and stir fry for a couple of minutes.
Add the cardamom chillies and fennel seeds and stir fry for a couple of minutes more, then drop the heat to low and add the garlic. Leave this mixture to fry gently for at least 10 minutes - the longer, the better, although keep an eye on it, as you don't want the onion to colour appreciably.
Meanwhile place a small heavy saucepan over a high heat and dry roast the cumin seeds, coriander seeds, cassia bark (or cinnamon if using) and cloves, however don't burn them or it will taste foul. Then take these roasted seeds and grind them (either with a mortar and pestle, or an electric coffee grinder).

Add this spice mixture to the pan, together with the ginger powder and turmeric powder and stir fry gently for a couple of minutes.
Following this, add the yoghurt to the mixture and fry gently until the most of the liquid has gone.
Then, add a 1/2 pint or so of boiling water and the tomato paste - the idea is to have the mixture pretty liquid at this stage. Finally, add the red pepper and meat (if using) and simmer for at least 1/2 hour until most of the liquid has gone and there is a thick, hot sauce (it may be necessary to add a little water if it dries out too much).

Serve with rice / Indian breads.

If you try it, I hope you like it :-)