Combine the sour cream and the baking soda in a separate bowl and set aside.
Place the flour, sugar, baking powder and salt together in a large bowl OR in the bowl that attaches to a stand mixer. Whisk together or use the paddle attachment in the stand mixer to fluff it up.
Place the butter into the flour mixture and either cut in with a pastry blender OR use the mixer. I have started using my mixer and will NEVER go back!!
Once the butter is cut in and there are chunks the size of peas,beat the egg and pour into the sour cram mixture. Combine.
Pour the egg and sour cream mixture into the flour. Combine until just moistened. Add in the rhubarb and the coconut, mix until just combined.
On a lightly floured surface, roll the dough into a log then cut into three disks.
Place each disk flat and flatten into a circle that's an inch thick and around 4-5 inches wide. Cut each circle into 6 equal triangles.
Place scones on a parchment lined backing sheet ( I fit 9 to a sheet and bake them all up at once) and bake in the oven for 20-25 minutes until nicely browned.