The food item in the photo is a mesquite bean. Mesquite bushes grow like weeds throughout the area, and are also very common in southwest US (introduced), Central and northern South America. These are leguminous trees and the beans (fruits) fall seasonally in the hottest months of the year. They are relatively high in protein, very high in carbohydrates, over 20% fiber and have a good calcium
hosphorus ratio.
Indigenous people often pulverize the dried bean to make a highly nutritious bread.
Because the scarcity of highly nutritious foods throughout the range of C. cornuta, it is not surprising that these lizards gobble the sweet beans with delight. However, as is the case with most herbivorous lizards, seasonal fruits offer only a part of the annual diet, and their relatively rich contents are offset by the low-nutritional value of the other foods commonly eaten.
There has been quite a bit of research conducted on mesquite beans, mostly as a supplemental feed for cattle and pigs. If you want to find more info on their nutritional value, just type "mesquite bean AND nutrional value" into a search engine.
Though I know about mesquite beans, I have not travelled to DR, and was not aware that cornuta gobbled them up (though it makes sense). Thanks for posting the photos.