Late goals earn Uruguay Lisbon victory
Uruguay missed Diego Forlan and strike partner Luis Suarez after they opted out of the squad for personal reasons.
After threatening only rarely against an organised Angolan side, the Latin Americans were indebted to debutant Hernandez.
After coming on as a second-half substitute, he earned the penalty that Cavani coolly slotted in after 84 minutes and six minutes later Hernandez netted with a delightful curling shot that flew into keeper Lama's net.
Oscar Tabarez, who guided the Uruguyans at the World Cup in South Africa, missed the game as he is in negotiations to renew his contract.
He was replaced for the friendly by under-20s coach Juan Verzeri.