Anything that makes a lovely jam will also make a lovely compote. Just peel, chop or dice and simmer with a little sugar and just the tiniest pinches of salt.
Slice up an onion and some potatoes and sautee them in some clarified butter (gee) or coconut oil with the curry leaves until the potatoes begin to get golden brown delicious spots on them. Continue to sautee while you add some grated turmeric root, dried coriander seed, ground cumin and salt. It will be a rather shocking fluorescent color, that means you’re doing it right. When the potatoes look done, they’re done. (Sometimes Dad made “Fluorescent Potatoes” with precooked and sliced potatoes to speed it up a bit.)
I have no idea what to do with a banana flower, sorry.
Do be aware that the splatter and spilled pieces of Fluorescent Potatoes *will *stain clothing and possibly some counters and cooktops (although a mild bleach solution took care of our counters/cooktop). Probably not the dish to serve if you’re hosting the Queen.
Turmeric in general, either powdered or fresh, is always a bit of a hassle in terms of staining. It’s usually the thing that makes most “curry powders” yellowish in hue, and has been used as a fabric dye as well. But I agree with WhyNot’s suggestion, or use the curry leaves and turmeric for some other kind of vegetable (cauliflower, for instance) that you want to have Indian flavors.