CARACAS, May 31 (Reuters) Venezuela’s opposition-led National Assembly voted to ask the US Congress to investigate what it said was an “immoral” deal in which Goldman Sachs Group Inc bought 2.8 billion dollar of Venezuela bonds for pennies on the dollar. The New York-based investment bank has come under fire from Venezuelan politicians and protesters in New York opposed to leftist President Nicolas Maduro, who said the deal provided the cash-strapped government hundreds of millions of dollars in badly needed hard currency. REUTERS