MVC :: How To Convert SelectListItem To Custom Type

Example: I create a custom type in my domain model (say a "Country" class with Id and Text fields)

A "Person" object have a property of the above type.

The Service class return a list of Countries (IEnumerable<Country> GetCountries();)

Now the ViewModel, derive from the "Person" object and have a member "Countries" which is IEnumerable<SelectListItem> Countries (It convert the Country collection from the service to a collection of SelectListItems.

I use the SelectLIst collection to populate my dropdown.

However when I submit the form, validation fail, obviously because the "Country" dropdown give a string value, while a Country object is expected.

So I need to cast this value from a string (using the "id" of the SelectListItem) to a Country object.

Where and how would be the right way to do this? (Another late night with me bing brain dead and probably overlooking the obvious).