Combine flour, sugar, yeast and baking soda in a large bowl. Mix until combined.
Beat the egg in a separate bowl.
Whisk in the water and buttermilk.
Combine this wet mixture with the flour mixture, then add the margarine and beat with an electric mixer until all of the dry ingredients are moist.
Use a kneading hook to knead the dough for 15 minutes or knead by hand.
Wrap the dough in plastic and place it in your refrigerator for 5-6 hours (as long as overnight) until the dough doubles in size.
Remove the plastic and press the dough out onto a lightly floured surface.
Flatten the dough with your hands for a bit, then use a rolling pin to shape the dough into a 20 inch long by 17 inch wide rectangle.
Use your hands to stretch the dough as necessary to the proper dimensions.
Use a spatula to spread 1/2 c of softened margarine over the dough, but leave the bottom 1 inch of dough uncoated with margarine.
Combine the brown sugar, cinnamon, and Xanthan gum in a medium bowl.
Pour the cinnamon/sugar onto the margarine and use your hands to spread it to the edges, leaving the bottom 1 inch uncovered with cinnamon. Run a rolling pin over the filling to flatten it into the margarine.
Roll the dough tightly starting at the top. Stretch the dough a little as you roll it down, so that you have 5 1/2 to 6 rotations by the time you get to the bottom.
Brush a little water over the botton 1 inch uncoated strip of dough and complete the rolling.
Mark the approximate middle of the dough roll, then use a ruler to make 3 marks every 2 1/2 inches to the left of the middle mark, and 3 marks every 2 1/2 inches to the right of the middle mark. Use a serrated knife to cut at each mark to make 6 rolls (the ends can be tossed).
Place the rolls evenly spaced out the parchment paper in a 9 x 13 inch baking pan.
Place the pan in your unheated oven along with a large saucepan of boiling water to proof the rolls. The rolls should proof for about 1 to 2 hours or until nearly full size in a pan.
Reheat the water in the pan to boiling after the first hour if the rolls are nearing full size.
When the rolls have proofed to almost full size, preheat a convection oven to 180 C. Bake for 16 - 20 minutes or until light brown and the rolls register around 76 C in the middle. Spin the pan around 180 degrees halfway through baking.
While the rolls bake, whip the butter cream cheese, vanilla, salt and lemon extract for 10 minutes on a high speed with a electric mixer until fluffy.
Add powdered sugar then mix again (slowly at first, then on high speed) for 30 seconds.
When the rolls come out of the oven, immediately to each with generous coating of frosting.
Enjoy
