Preheat oven to 350℉ and line a baking sheet with parchment paper.
Using an electric mixer, combine psyllium powder, coconut flour, Keto Chow, baking soda, and baking powder.
Add the egg whites, oil, and vinegar and mix on low speed until combined.
Carefully pour in the hot water with the mixer off, then mix again on low speed.
When the water has been incorporated, mix on medium speed until a soft dough forms.
Divide dough into six pieces and shape into balls.
Mix the egg yolk with a teaspoon of water and brush the egg wash over each roll.
Place on the baking sheet, pat down lightly, and sprinkle with sesame or poppy seeds.
Bake in the preheated oven 30-40 minutes, or until they are brown, puffed, and round. They should sound slightly hollow when tapped on the bottom, and should hold their shape when gently touched.
Cool for ten minutes, then transfer to a basket lined with a clean cloth or napkin to keep warm.
The rolls will keep in an airtight container in the refrigerator for up to a week or in the freezer for up to three months.