Korean/nashi pear
A round, very juicy pear with crisp, slightly grainy flesh, closer to an apple than to a soft pear.
Nashi pears are found in Asian grocers and often in well-stocked supermarkets or markets, mainly in autumn and winter; the Korean varieties are usually especially large and golden-brown.
Substitute:
A crisp, juicy apple or a firm, not quite ripe pear comes close. Eaten raw the difference is clear, while in marinades it hardly shows; there the result is a little less juicy and mildly sweet.