I've heard a thousand times that legumes themselves are "incomplete proteins", meaning they are deficient in some amino acid, so it is beneficial to combine them with grains, which have the amino acid that legumes lack.
In all the websites I've read, the lacking amino acid in legumes is methionine, which grains have supposedly a lot.
However, when trying to estimate how much of this amino acid I need to consume daily, I found something really confusing, legumes actually have more of all amino acids than grains (yes, including methionine).
Yet, everybody is claiming that they need to be combined, and this isn't like a debate, everybody seems to agree.
So why is it that mixing these two foods make "complete proteins"?
I would also appreciate if you would link a source, although is not necessary