Their table would be graced by pieces of aubergine the size of an index finger, fried and dusted with cumin.這里the size of...是作后置定語嘛？它不是個名詞短語嗎？

Their table would be graced by pieces of aubergine the size of an index finger, fried and dusted with cumin.

是的，網友判斷正確。

劃線部分是名詞性詞組，作 pieces of aubergine 的定語。等于說：

Their table would be graced by pieces of aubergine which are the size of an index finger, fried and dusted with cumin.

the size of...作定語舉例：

The British pavilion is an impressive steel and glass construction the size of Westminster Abbey.

這座英式亭閣是讓人贊嘆的鋼和玻璃建筑，大小和威斯敏斯特教堂相當。

《柯林斯高階英漢雙解學習詞典》

It may even be possible to make computers the size of a pinhead one day.

甚至有一天計算機都可能做成釘頭那樣大小。

《柯林斯高階英漢雙解學習詞典》

If it were a country, California would be one with more people than Canada and an economy the size of Chinas.

假如它是一個國家，那樣加利福尼亞州將是一個人口超越加拿大，而經濟規模與中國相當的強國。