Beat the salt, butter, sugar and egg in a large bowl. Add flour and warm water and mix. Knead on floured surface til dough is smooth; return to bowl and cover with dry towel. Let rest15 minutes. Divide dough into 20 balls, coat with flour and press into flat 3 inch circles. Stack between wax paper til ready to fry.
Heat oil to 400 in skillet and fry one bunuelo at a time 30 seconds on each side til golden and crispy. Remove and drain on paper towels. While still hot. sprinkle with cinnamon sugar.
Best eaten warm. Can be stored in airtight containers and reheated in oven at 350 for 6 to 8 minutes til crisp.