In a large mixer bowl, combine 2 cups flour, yeast and 3 teaspoons dry salad dressing mix. Reserve remaining mix. Heat buttermilk, water and shortening until warm (120-130~), shortening need not melt. Add to flour mixture. Add egg. Blend until moistened; beat 3 minutes at medium speed. Gradually add enough flour to make a firm dough. Knead on a well floured surface until smooth and elastic (5-10 minutes). Place in greased bowl; turn to grease top. Cover; let rise in warm oven (turn on lowest setting for 1 minute, then turn off) for 20 minutes. Punch down dough; divide into 2 parts. On lightly floured surface, roll or pat each part to a 12x7 inch rectangle. Starting with longer side, roll up tightly sealing edges and ends. Place seamside down on greased cookie sheet. Make diagonal slashes about 5 cm apart in tops of loaves. Cover; let rise in warm oven until light and doubled, about 30 minutes. Bake in preheated 190ºC oven for 25 to 30 minutes. While warm, brush with melted butter; sprinkle with 1 teaspoon reserved salad dressing mix. Cool on wire racks.