Preheat oven to 325F (165 °C). Line baking sheet with foil or waxed paper; set aside. In a large bowl, beat egg whites and lemon juice until stiff peaks form. While continuing to beat, gradually add sugar. Fold in coconut or chopped nuts until mixture is evenly blended. Drop mixture by teaspoonfuls onto lined baking sheets. Top each cookie with a hazelnut. Bake 30 minutes. If cookie starts to brown, slightly reduce the oven temperature. Cookies should not brown. Remove cookies from baking sheet and place onto cooling racks. When cooled store in a tightly sealed container. If cookies are to be stored longer than 1 to 2 days, add a lemon or apple wedge to the container. This will keep the cookies from becoming hard. Makes approximately 30 cookies.