Learning how to send childrens snacks when living in a foreign country

I live in Sweden.  I have now lived in Sweden for approximately 12 years, with a brief break back in the US in the early part of this century.  I even have dual Swedish and American citizenship now!  Yet, despite this, I still seem to fail at basic things such as packing a childrens lunch for a school field trip.

The normal note comes home: on such and such a day the whole school will be going to a science museum for the whole day.  Please pack a nutricious lunch and snack to send with your child.

Now, when I think nutricious I think sandwich, carrot sticks,, a small bag with half a cup of potatoe chips, a banana and one homemade oatmeal raisin cookie.  And water to drink.  Could anyone do any better??  To up the nutricious, I actually made a vegetarian sandwich on homemade wheat bread, with avacado, tomatoe, lettuce, onions, etc. etc.  (Those years in high school working at Subway really paid off practically come motherhood!)

I was thinking I must be about to win the mother-of-the-year award in Sweden.  Instead, my child came home from school in tears, and starving to death.  Why?  His teachers did not let him eat his lunch - because of the cookie!

According to said child, every other child had three items in their lunch and snack: cinnamon buns for snack, Swedish pancakes (like crepes) for lunch, and a drink of saft (like homemade Koolaid).  When I asked the teachers about this, their response was, "Well, that is nutricious." I have cooked all of the above, and there is no way they are more nutricious than the lunch I packed and one cookie.  When I pointed out that it was no nutricious, they shrugged, "Well, it's what we are used to children eating here in Sweden."