In a liquid measuring cup, add the vinegar and milk and set aside to curdle (this mimics buttermilk) After a few minutes, this is where you add the chia meal and psyllium husks too.
Mix in the honey or stevia.
In a medium bowl, whisk together all dry ingredients.
Using a pastry cutter, work the shortening and butter in until it is chunky in appearance, and some larger chunks of fat still remain.
Stir in the milk and egg whites (if using). Stirring the least amount possible! With the egg free version, dumping the whole gelatinous mixture in requires some coaxing with your hands...I mix by hand until all the dry and wet are incorporated.
Gather the dough in your hands, forming a ball. Try and handle the dough as little as possible to help keep the flaky texture.
Gather large chunks of dough in your hands, and mold them into 1.5 inch- 1.75 inch high mounds , they will not spread or rise too much. I also pat the dough into a rectangle or square and cut them into cubes.
Bake for 12-15 minutes or until lightly golden brown.(I have noticed the egg free version bakes a bit longer, bake until just firm and set.)