You just made a food pyramid that isn’t stupid.

Only truly cheap if you make it yourself. That’s why I commented below on the missing item of “effort”.

The one thing missing from the trinity is “effort”. For instance, you could make any Dal, which would fit the trinity, but takes a lot of time. There are books with hundreds of Dal recipes that all taste different and work, too. And this is just one example. Less than a dollar a meal if made in bulk with rice.