On most long-distance trains there will be a restaurant car serving freshly cooked local dishes and a variety of hot and cold drinks. Restaurant cards are not open 24 hours a day so keep a note of opening times.
As is common on Russian trains, opening times will be in Moscow time not local time.
On some trains there will also be snack trolleys wheeled through the train at regularl intervals. If there's no snack trolleys you can often purchase snacks and drinks from the provodnista's cabin.
Each carriage will have a samovar for hot water so you can take tea, coffee, instant noodles and soups. You can pack them in advance of buy them along the way, theyre available at most stations or supermarkets near the stations.
Station shops won't stay open 24/7 so be sure to stock up on supplies during daytime stops.
One of the more interesting places to shop, especially at smaller stops, is with local traders w ho sell local produce from the train platform or through the windows of each carriage.
It's also best to pack your own cutlery and travel mug.