If you have leftover onions, peppers ,garlic, ginger, carrots etc.
Fry everything except the carrots (steam or boil those, unless they’re cooked leftovers) then add some garam masala powder or paste, paprika, cinnamon, ground ginger and turmeric, about a tablespoon of each, or to your taste.
Add in a tin of coconut milk and a tin of chopped tomatoes. Use a stick blender or cup blender, to make a paste.
This makes a curry base, just as the restaurants do.
You can freeze it into portions (the volume that would fill a tin of tomatoes serves 2) Then when you come to make a curry, fry a few tablespoon of the curry paste of your choice, Madras, Korma etc. Add your protein, prawns, chicken, beef, Quorn etc and cook, then add your base mix. Makes great curries.