I don't cave into trantrums about food or anything else.

At interview I am really clear that I provide one meal without options and if a child decides not to eat it, then they will be extra hungry when the next meal time rolls around. I will neither force fed a child to get them to try something nor will I pander to picky eaters. This is the meal, take it or leave it.

If a child screamed for 10 mins about a meal I had provided, then the meal would be removed but I wouldn't give them the food items I know they wanted in exchange. I get it's really hard and disruptive but IMO, giving in just reinforces the behaviour.

Depending on age, I do have a two mouthfuls rule. If someone thinks they don't like something, they have to try two mouthfuls and if they still don't like it, fair enough. Again, they won't be offered an alternative since all of my meals have at least two items for a snack and three for a meal. They can eat the other things on their plates.

All that said, if a child really has a dislike of one item and it's out of character, I'll bear that in mind with future meal planning. I had one little boy who really didn't like peas. He'd eat any other vegetable but he truly disliked peas. For me, it's no big deal to plan to serve a different veg in that situation.

I would just offer a small portion of the real lunch. If he doesn't eat it, so be it. Sooner or later, with a busy environment, he's going to get hungry. It might be a heck of a rough ride for a few days since he's used to increasing the tantrum until he wins, so be prepared for an all out revolt on his part since that's worked to date and likely will continue to work at home.

I would also take the go-to Cheerios off the menu completely for the time being. If they remain, even as part of the routine go-to snacks, he'll realize that the next meal might just be the one he's hoping for and hold on for that.

Good luck. It's going to be a nightmare to break but will only get harder the longer it goes on so sooner or later, someone's going to have to deal with it head on.