Add in the the butter chunks and pulse until broken up but still some pea sized pieces of butter remain visible. If using coconut oil, place the whole bowl in the freezer for 10-15 minutes to chill before continuing.
Add in the egg and pulse a couple of times to mix.
Add in kefir, and pulse until JUST starting to come together. Start with 1/2 cup and add more only if necessary. The dough should press together easily.
Dump out onto a floured work surface (I use more of the starch), and knead a couple of times gently to bring the dough together and and make a cohesive ball.