Mine gets spring mix, Mazuri, romaine, red and green leaf lettuce, collard greens. Just to name a few. I switch what she gets to try and give her something different every few days.
Your Russian needs a diet of leafy greens. It needs a variety to stay healthy.
It cannot digest sugar properly, so fruit, including bell pepper, tomato and carrot should only be fed very occasionally.
Make a list of all the plants you can find outside (pesticide and herbicide free) and in the grocery store and then look them up on the Tortoise Table Plant Database to find out what's good to feed. http://www.thetortoisetable.org.uk/site/plant_database_14.asp Buy something different each time you shop so he gets variety.