Various spices and dried herbs? Get a whole bunch of different ones, perhaps even some premixed from India (though unnecessary, but may be available even in places like Lidl every now and then IIRC)

I always fall back on chicken breast, what most people seem to find bland and dry. Well, you can mix up some spices together, figure out some combinations you like and put them on your protein/vegetable of choice (will work well with olive oil too as another person mentioned). Want it done quick? Chop it up into smaller pieces and throw in a frying pan. Don’t want it oily? Swap it out for butter (just use lower heat) although I prefer sunflower oil.

You’ll probably have few that you eventually always use in combination with others. E.g. my favorite to use are sweet paprika, coriander and turmeric. Turmeric seems kinda crap on its own, but works well with other spices. Coriander doesn’t need much added, if anything and smells good imo and paprika just goes well on lots of various stuff (note that smoked or plain paprika is also very different from sweet kind though)