Our basic leftover chicken curry:
Cook a couple of onions, slooooowwwwly, in ghee or vegetable oil. Add chopped garlic, grated ginger, chilli (they freeze well chopped) to taste - you'll need to experiment - my lot like it heavy on the garlic but easy on the chilli - then any veg which needs using up e.g. chopped carrot, peppers, zucchini, aubergine etc along with a teaspoon each of cumin, coriander & turmeric. I like to chuck some fenugreek in too.
Add half a dozen fresh ripe tomatoes (or a tin) OR tin of coconut milk for a creamy curry. If kids are weird about veg you can blend the sauce at this stage, once the tomatoes if using have cooked down a bit.
Chop your chicken & throw in, along with a handful of frozen peas, spinach or beans. Simmer gently to hear through & finish with a teaspoon of garam masala & chopped fresh coriander (which also freezes well so I buy a big bunch, chop & freeze).
Serve with steamed basmati rice &/or naan.
Also good with lentils added with the veg or a tin of chick peas instead of/as well as the chicken.
Not terribly authentic but a popular staple here!