McDonald’s is set to reintroduce its Quarter Pounder burger to about 900 U.S. locations after a temporary removal linked to a recent E. coli outbreak. The burger will be served without slivered onions while health authorities continue investigating. McDonald's has halted use of Taylor Farms as an onion supplier, as officials suspect their onions may be linked to the outbreak. McDonald's USA President Joe Erlinger apologized, expressing regret for the situation and its impact on customers.