Manchego Viejo is Mexican Manchego cheese that has been aged, giving it a sharp taste and firm body that can be grated, shaved or sliced. The cheese is yellow, whereas unaged Manchego is whitish.
There is also a Spanish “Queso Manchego Viejo”, which is aged at least 3 months.
Substitutes
Any Pecorino Cheese, Dry Monterey, Parmesan, or Grana Padano.