"Metal tongs" refers to a tool made of metal which has two long arms with flat, often ridged, ends used for gripping and handling objects securely. Full definition
We were locally impacted as field workers Roughnecks on a drilling rig in Greely, CO use metal tongs weighing hundreds of pounds to make connections between 30» sections of drill pipe. (rentcody.com)
Using a pair of metal tongs hold an aubergine in the flames and keep turning until all of the skin is charred and the shape has collapsed, then repeat with the rest of the aubergines. (meatfreemondays.com)
While the soup simmers, hold the whole bell pepper with metal tongs over an open flame on the stovetop. (epicurious.com)