Making Souk. When do I add these Moroccan spices?
I cannot seem to find references to a Moroccan dish named "Souk". Rather, souk is the Arabic word for bazaar or marketplace. Perhaps it refers to the sellers of your spice mix and not a dish to use it in? I will assume you have your hands on a typical Moroccan spice blend such as ras el hanout.

In any case, to get the best flavor out of your spices, you need to bloom them in oil. Heat oil until shimmering and fry any aromatics you are using. Add the spices, and cook for a few second. Recipes usually tell you to cook "until fragrant", but really, a few seconds should do. It is very easy to burn ground spices. Immediately add the beans and the cooking liquid, simmering until tender.

A good inspiration would be this recipe for spiced black-eyed peas. Although it uses Indian spices, the basic technique would be the same.