We are not done with Ishaq b. Sulaiman al-Israili yet. About legumes – and again, we have almost recipes.
(…) Some cook them (beans) in water, and some roast them by the fire. Those (beans) that are cooked in water are more laudable because the water takes much windiness and grossness away from them, especially if the first water is thrown away and other water substituted. And two ways also apply here: either they are cooked with their shells or without them. Those that are cooked in water with their shell are hard to digest and windy (…) Those cooked without their shells are less windy and faster to digest. And if a sauce is made for them with some heating ingredients (such as long pepper, ginger, and almond oil) it is the perfect medicine for the act of coition. They are sometimes also eaten with mint, oregano, cumin and similar ingredients which diminish their windiness and inflation even more. Those that are roasted by the fire have less windiness, and they are very hard to digest except is they are soaked in water after roasting and eaten with cumin, mint and oregano. …
(…) Lentils are cooked with their shells and afterwards cleaned and mixed with salt and oil and given to those that have a constriction of the belly, and if the first water is thrown out and other substituted, their solving power diminishes. If they are cooked without their shells and the first water discarded and a second substituted, they are rendered more easily digested. (…)
(…) to restrict choleric eructations, first clean them of their shells, then they are cooked, the first water discarded, a second substituted, and when cooked, mixed with vinegar and leaves and seeds of broadleaf plantain (plantago maior), quinces, sour apples, medlars, and similar. But if you wish to eat them instead to warm and strengthen the stomach, you mix them with aromatic red or black wine instead. Those who eat them to loosen the belly eat them with beet (sicla) or orach or gourd or jute mallow. And they are eaten cooked in various manners for food: Sometimes they are eaten with oil and vinegar. And sometimes with fresh meat, and sometimes with dried and salted meat. If they are eaten with oil and vinegar, they offer little nourishment, those eaten with fresh meat offer more. Those eaten with dried and salted meat are a bad and harmful food (…) If you wish to improve it, so that it causes no harm, clean them (the lentils) of their shells and when they are cooked in water, throw it out and substitute other (water), and afterwards, season them with vinegar, oregano, mint, pepper, cumin, and either almond or sesame oil. (…)
(…) They are of two kinds, white and dark red (subrufi). The white ones are less hot and more humid, which is why they are of grosser nourishment and harder to digest and produce gross and phlegmatic humours. If you wish to lessen their grossness, first boil them, then clean them of their shells, and eat the cleaned ones with obsomagarum, oil cumin and pepper. If the are white and green (fresh) ones, they are to be eaten cleaned of their skins, with salt, mustard, oregano and pepper, and unmixed wine should be drunk with them strongly.
I will start by admitting I do not know what faseolis are. They are clearly a kind of legume and clearly not the modern phaseolus beans – those are New World species. The description of them coming in two colours would suggest chickpeas except that ciceres have their own chapter. In other contexts, I have followed widespread practice in assuming the word refers to black-eyed peas (vigna unguiculata), an African legume familiar in Southern Europe at the time. That may well be the answer here, too.
I have never tried roasting beans – that is of course fava beans, vicia faba – but I am curious to try now. And of course you may want to try a sauce of ginger and long pepper on almond oil if you have plans for the evening, but I personally would not trust Constantinus Africanus on matters of the bedchamber.
When we are talking about lentils, it should be pointed out that the mustard very likely refers to mustard greens, not mustardseed or made mustard, and the beet – sicla – also is most probably a reference to beet greens, not the root. One of my absolute favourite recipes from Apicius (3.11.2 in betas elixas) is owed to just that misunderstanding. Red beetroots served with oil and mustard is wonderful, but not at all what the original intends.
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.