For several oriental recipes like couscous or chorba, one use a special mix of spices that can be find in supermarket or ethnic groceries.
If you can't find a ready-made mix of couscous spices, you can make your own from: cumin, coriander (ground), cinnamon, nutmeg, ginger, cardamom and turmeric. Paprika, cloves and caraway are also sometimes used.
By "mash powder" do you mean mash potato powder?
If so, yes you can, see how to on this chicken recipe : chicken breasts in a potato crust.
Can I use potentiometer mash powder to make cutlets?