What are the essential amino acids which most plant-based foods are low in one or more of these amino acids? (Answer： lysine, methionine and tryptophan)

Essential Amino Acids and 

limiting amino acids

Info source:

http://healthyeating.sfgate.com/nutrients-consist-essential-amino-acids-nonessential-amino-acids-3627.html

Essential acids are those that the body can't make for itself. These include tryptophan, methionine, leucine, lysine, isoleucine, histidine, threonine, phenylalanine and valine. 

Those that are most often of concern, called limiting amino acids, are lysine, methionine and tryptophan, since most plant-based foods are low in one or more of these amino acids.