I make these for lunch at least once a week. Just guessing at the ingredient amounts as I prep the veggies in advance at the beginning of the week and then use throughout. They pack really well, wrapped up in foil and they don't get soggy or leak. I would imagine they would make a great picnic food.
This recipe is from the Christian Science Monitor. It is gorgeous when assembled and absolutely delicious prepared and served with a dab of goat cheese and crusty french bread. Choose only skinny vegetables that will slice uniformly in size.