Here is one I use for chicken or vegetables.
One large chopped onion
One red and one green chilli (if you want it hotter, just use red chillis) finely chopped
A thumb sized piece of fresh ginger chopped finely
Two large cloves of garlic
A small cooking apple, grated
Juice of half a small lemon
2 teaspoons of turmeric
Half a teaspoon of cumin seeds ground
1 teaspoon ground coriander
Seeds from 6 or 7 cardamom pods, ground
Quarter teaspoon chilli powder
1 teaspoon mustard seeds (optional)
1 teaspoon Garam masala
Three quarters of a pint of good chicken stock or vegetable stock
One tablespoonful of tomato purée.
Heat a tablespoonful of oil in a large pan and fry the onion, finely chopped chillis, garlic and ginger on a low heat . Add the cooking apple and cook until apple and onion are softened but not coloured. In a separate small pan, dry fry the spices for a minute or so to release the oils but be careful not to burn them. Add the spices and the tomato purée, and a little of the stock to the onion mixture to make a paste and cook for a few minutes. Add lemon juice to taste and half a teaspoon of salt (optional). Gradually add more of the stock until the sauce is the consistency you want, but you can always add ground almonds or creamed coconut to thicken it. Creamed coconut will also dissipate any excessive heat.
To this sauce I will add chicken pieces which have been browned, and the garam masala, then cook for a further half an hour until the chicken is cooked. It is also a good base for vegetable curry.