hehe I can just imagine him with the orange things. DD went through that stage for a while.
I always send her with dinner type lunches. eg, roast, spag bol, vegie muffins (although they had cheese in them but you could do without), chicken drumsticks and pasta or amaranth or something. Banana bread? with some wholemeal flour? I guess this all depends on if you have a fridge at his school though or you could get one of those fridge to go lunchboxes.
DD will always eat frozen peas or pick them out of the fresh shells, and they are really easy, have you tried that?
Also you could try growing something in your yard, cherry toms grow like crazy in a pot, and corn is pretty easy. I think thats worked for dd getting her interested in vegies.
Maybe try substituting vegimite for the unpasturised miso paste you get from the health food shops? He might like it because its salty and has lots of probiotics which should be good for his bowel.
Oh also avocado? Does he like that? I love avocado and vegemite together in a sanger.
Have you tried him on sprouts? He can grow them at home himself and dd likes them.
Have you tried sheeps milk yoghurt? they have some nice ones at the health food store, and because its cultured and sheeps milk it might be ok.