Combine flour, nuts and sugar. Add pareve margarine and vanilla, blending with a fork. Work dough with hands into a ball. Take about 2 tsp. Dough and roll between fingers. Place on an ungreased cookie sheet and shape into a crescent. Repeat until all dough is used. Bake at 325* for 10 - 12 minutes. Sprinkle with icing sugar while hot.