Large left-sided pancreatic tumors are frequently associated with portal vein (PV) and/or superior mesenteric vein (SMV) occlusion. Traditionally, vein reconstruction is deferred until after removal of the tumor. However, division of venous collaterals, as is done in a typical left-to-right fashion, leads to progressive portal hypertension and increased risk of variceal hemorrhage during the dissection. Conversely, early PV/SMV resection and reconstruction restores mesenteric-portal flow and decompresses varices, thereby enabling a safer and easier right-to-left pancreatic resection. This "How I Do It" report describes the technique and advantages of a "reconstruction-first" approach for large left-sided pancreatic tumors with venous involvement and left-sided portal hypertension.