Hello,
In the referenced article Table 4 (page 7 of the PDF) shows composition in essential amino acids of mentioned vegetal foods and all these plants contain all essential amino acids. In Table 5 (page 8 PDF) Amounts of sample foods required to provide [B] a total amount of EAAs equal to the recommended daily sum of total EAAs we can see that the smallest sample of food required is soybean. Authors have taken the protein content and amino acid composition of the foods from published tables of INRAN (the Italian National Institute for Research in Foods and Nutrition: INRAN. "Tabelle di composizione degli alimenti." Istituto Nazionale di Ricerca per gli Alimenti e la Nutrizione. Roma (Italy). 2009. Available at: http://nut.entecra.it/646/tabelle_di_composizione_degli_alimenti.htm. (Accessed 15th October 2015).) However, the link to the table of food composition is not working. On the INRAN website (http://www.fao.org/infoods/infoods/tables-and-databases/en/) there are international food composition tables/databases but I haven't check if they show same or similar numbers. I guess that the authors are not aware of this.
If the reference from Scientific Report is insufficient I guess I will try to find another one.
Kind regards Grzegorz Mynarczuk