SLICED DUCK BREAST ON COUS COUS   Duck is little used in The United States although it is plentiful and very good. Try experimenting with it as I have done ; you shall be rewarded.   I have been experimenting with duck for many years. The problem of course, is all the subcutaneous fat. I think I have tried all the various ethnic methods of removing it. I have parboiled it, like the Chinese and hung it up to dry for a day. I have even attacked the duck with a hair dryer. Still it was too oily. In the end, I simply cut the skin and the fat off before cooking. The crispy duck skin is one of the best parts of the dish so don't throw it away. I render it slowly in a frying pan until most of the fat is out and it is crispy like a pork rind. Then I use it as a garnish on top of the duck. The duck may come back not entirely eaten, but the skins are always gone. The duck breasts which you can buy now make everything easy. If you skin them and render the fat very slowly anytime during the day, you can grill them over charcoal for just a few minutes before serving. They do not grill well with the skin as the fat burns causing the meat to become black and covered with ashes. The meat should be very rare like a steak. It is very good and guests can't believe that it is duck. Here I serve it on a bed of cous cous with scallions, zucchinis, and cherry garden tomatoes tossed with olive oil and basil.