I don't think you're overreacting, it certainly isn't the most nutritious meal around and it sounds gross to me too. There is a possibility that Lily might have enjoyed it - toddlers can have wierd tastes sometimes. My DH feeds Yasin wierd food too and dresses him daggy. Sometimes I go off at him about it but as often as possible I try to let it slide. Lots of my friends have husbands who never look after thier children and I could count the number of times my father looked after me on one hand so I think that I'm quite lucky to have a partner who is so into being a Dad. He doesn't always do things the way I would like him to but if I want everything done my way then I would have to do everything myself IYKWIM. I geuss that for me when I wiegh up the gross food and dodgy clothes against the me time and the value to my boys of having a loving, attentive Dad it doesn't seem such a bad trade off IYKWIM.
I think that Rachel's idea of suggesting a few alternatives for next time is a good one. Jacob might just be a bit clueless about what foods to prepare so if you point him in the direction of the vegemite or cheese he might make a better sandwich next time.