What kind of vegetables do we get in Warsaw?
Have a look at this site: warsawtour.pl/en/warsaw-for.../markets-3520.htmlCached
You won't find everything you'd get back home, but you're sure to find okra, spinach, all kinds of squashes and, of course, potatoes. Spices will be a bit trickier. I've never seen asafoetida (hing) here. Perhaps you could bring some (well wrapped) if you use it.
You need an unbrella. If you're staying for the winter, you'll need warm boots and a good coat, but you can buy those here quite cheap. Save your baggage allowance. There are Indian restaurants, but be prepared for the shock of your life when you see the prices.