Preheat your oven to 425 degrees. Line a baking sheet with parchment paper and set it aside.

In a medium-sized bowl, whisk together the flour, salt, baking powder, and sugar until combined. Add the cold butter and cut it into the flour with a fork or your fingers until the pieces of butter are roughly the size of peas or a bit smaller. Once you do this, place the bowl in the freezer to chill for about 10 minutes.

While the flour and butter mixture chills in the freezer, Combine the ground flax seed and hot water in a small bowl. Mix, then set it aside to thicken for about 8-10 minutes. After it thickens, add the cold plant milk and apple cider vinegar. Whisk to combine.

Remove the bowl from the freezer. Add the wet ingredients to the bowl, then begin to mix with a wooden spoon or spatula. Mix until you have a cohesive dough. I often bring the last of it together by hand to make sure I incorporate all of the flour. Form the dough into a one-inch thick round. It will be roughly 4-5 inches in diameter. Wrap the dough in parchment or plastic wrap and set it back in the freezer for 10 minutes.

Remove the dough round from the freezer and set it on your parchment-lined baking sheet. Sprinkle the top of the dough with a bit of cane sugar, then cut it into either four or six equal wedges. Separate the wedges out onto the lined baking sheet, making sure to leave a couple of inches between each scone. Bake the scones in the preheated 425 degree oven 15-18 minutes or until they have puffed up and the tops and edges are turning golden brown. 

Cool the scones on a wire rack for 20 minutes before eating.

These scones are best the day they are made but leftovers can be kept in an airtight container at room temperature and enjoyed within 2 days.