Add the walnuts, coconut flour, psyllium husk powder, baking powder, and salt to a food processor, and mix until the walnuts are ground, and everything looks like flour.
Add the eggs and apple cider vinegar and pulse a few times until the eggs get incorporated into the dry ingredients. With the food processor running on low, gradually add the hot water. You should get a ball of homogenous, stiff dough.
Take the dough out, shape it into a ball, then portion it into 6 or 8 pieces (6 for bigger rolls, like for hamburgers, and 8 for smaller rolls, for sliders).
Shape into balls. If you want to top the rolls, dip the top in warm water, then dip them again into the sesame seeds.
Arrange on a baking sheet on parchment paper. In a preheated oven at 350F/180C, bake for 45 minutes, without peaking in, then turn off the heat and let them in the oven for another 30 minutes.