28-year-old Cristhian Stuani joined Boro in August 2015.
The Uruguay international began his professional football career at Uruguayian side, Danubio in the Primera Division.
He was signed by Italian side Reggina Calcio in Serie A in 2008 and had loan spells at Albacete, Levante, Racing Santander and Espanyol.
The striker made a permanent switch to Espanyol in 2013 where he scored 15 goals in 47 appearances in the 2014/15 season.
He made his international debut for Uruguay in November 2012 in a 3-1 away friendly win against Poland.