They love fresh veg

Just a tiny bit every day so she eats it all otherwise they tend to pouch and hoard it, and you don't want it going rotten under the bedding somewhere! Rule of thumb is a piece no bigger than their ear or about 1cm cubed size (which is very slightly bigger usually). I tend to give something different every two or three days - so maybe cucumber one day, broccoli the next, baby corn the day after and so on. Some people give a small piece of bell pepper or spinach or cauliflower. There's a list of safe fruit and veg on the article below
Many human foods are safe for hamsters, but some are toxic to hamsters. Our hamster site has a researched and referenced food list gives up to date information on safe and unsafe foods for hamsters.
www.thehamsterforum.com