I think you are asking too much of these kids. They may not want to be vegetarians. They may want to be meat eaters...lol.
I think that if you are really wanting to do this then perhaps moving away from the red meats and only using fish and chicken would be a nice first step.
My granddaughter will not eat anything that is mixed together. Like a casserole. The will eat two or three different HB helpers though. You could buy some Morningstar Beef Crumbles and make it with them instead. They are vegetable stuff made to look and taste like different meats that Walmart carries in the frozen foods section.
There is also Turkey ground meat. I would use that in dishes that resemble Chicken Helper type dishes or Tuna Helper type dishes. Kids like foods like that as a general rule is all I am saying. I can't stand Tuna smell and I am not buying Turkey anything.
So, what would I do it I were making a menu for you....thinking....thinking.....thinking.
What about investing in some meat substitutes that are sold in bulk. We have eaten this and did not know it was not HB meat. We get it from places like Emergency Essentials or some of the other links below.
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What it is:
http://en.wikipedia.org/wiki/Textured_vegetable_protein
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Where you can get it:
Emergency Essentials has everything you could ever want to cook totally vegeterain:
http://beprepared.com/
TVP:
http://beprepared.com/search.asp?t=ss&ss=tvp&imag...
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This company has some of the best tasting food that is around for food storage. I bought some on sale at Walmart and we ate it up that week instead of storing it. It looked like Military rations.
http://www.harmonyhousefoods.com/
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Amazon sells it:
http://www.amazon.com/Textured-Vegetable-Protein-Chunks-l...
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There are lots of places to buy foods that will make any dish taste good and look appealing to kids. I have a picky eater and I have to dish out the pasta before putting the sauce on, I have to make sure her mac and cheese is just mixed so so. There are lots of ways to do this and not be a short order cook but it is often the case that you have to serve the food in different ways to each child.
Here's an article about TVP that talks about how it has changed over the years.
https://www.usaemergencysupply.com/information_center/all...