If you are really struggling, fruit juice counts as 1 and is usually an easy one to get kids to accept.  I think as well that the amount to count is scaled down for kids although I am not sure about this.

I grate carrot and add it to allsorts - homemade pizza has sneaky carrot in the tomato sauce and the kids love adding their own toppings.

Don't forget dried fruits count too.

Good luck - my eldest was fine until she started school.....  bit better now she watches the little un eat almost everything (she loves tomatoes, particularly the vine ripened or cherry, or baby plum and they make up one of her five almost everyday or she complains!)

i have a great recipe for hidden veg pasta sauce, i have trouble getting my daughter to eat veg so this is great cause i can put courgette, carrot, broccoli, ect in this and then blitz it all down with some veg stock and tinned chopped tomatoes so its just a tomato looking sauce and she wolfs it down with pasta i wil try to remember to post it on here tomorrow .... and see what else is in my recipe folder .... i take my daughter to a parent and toddler cookery group so we make loads of lovely and healthy recipes and it means you can get them to try the food without spending loads of money and time in the kitchen only to find out they don't like it   ... i would recomend to anyone who has one in their area that they give it a go, it teaches them to be safe in the kitchen and learn what different fruit and veg are ... and when you all sit round to try it at the end they see other kids eating the same as them and they are more likely to try it

I have a book called Sneaky Chef.  I got it from Amazon a while ago, and it includes some great ways to add extra fruit and veg to food.  There are tons of recipies for puree's that you can add such as carrot and sweet potato which I add to loads of things like tomato sauce and even macaroni cheese.  There is one for spinach and blueberries, and it gives a recipe for brownies. 

I was very sceptical at first, but they actually weren't bad!  Instead of hiding it though, I got my boys to help me make the puree's, and they see me adding it to the food when they help me cook.  It's only a small amount, but every little helps

A brilliant book for baking with vegetables is Red Velvet Chocolate Heartache by Harry Eastwood. She even makes cakes with stuff like turnips.  The aubergine chocolate cake is wonderful.