I was firmly convinced that had to be a description of Middle Eastern practice because aubergines were long considered a novelty even there, but it is one of the places that mention pork. I guess they could have been widespread in Sicily already by the 1100s.
p. 470 f. of aubergines
(…) but they are of less harm if they are tempered and split and filled with salt and then much later thrown into hot water and afterwards placed in different water and washed two or three times. After then are washed in water, they will lack all their blackness and they are then boiled and, the water having been discarded, are cooked again with fat meat of cattle or sheep or pork or similar. Those who wish to eat them without meat cook them with vinegar, oil of unripe olives, obsomagarum and similar things.
Medieval recipe books often take great pains to draw out the bitterness from aubergines, and heirloom varieties can be very intense even today. Your average modern supermarket variety would probably not profit from that kind of treatment, but the general preparation instructions – cook with meat or prepare with vinegar, oil and something umami – still sound attractive.
Isaac Iudaeus de diaetis universalibus et particularibus, originally written in Arabic in the late ninth or early tenth century, was translated and adapted by Constantinus Africanus in the late 11th century and circulated widely in Italy and beyond soon afterwards. While the original applies to a different context, it is still reasonable to use it as a guide to the advice that Siculo-Normans would have found useful. It is an open question how much the original was altered in translation – I cannot say since I read no Arabic. However, the extensive reference to eating pork suggests that some alterations took place.