Preheat the oven to 180C/350F degrees.

In a bowl add the coconut flour, ground flaxseed, psyllium husk powder, baking powder, salt and seasonings. Mix well.

In another bowl, whisk the egg whites until stiff.

Add the egg yolks to the coconut flour mixture and stir thoroughly.

Add the olive oil and mix well. Then stir in the apple cider vinegar.

Gently fold in the egg whites.

Add the boiling water and gently mix. If the mixture looks a bit too soft, let it sit for at least 10 minutes to firm up.

Split the mixture into 4 sections and take one section. Using your hands, make it into a sandwich sub shape.

Place on a baking tray lined with parchment paper, and repeat for the rest of the dough.

Bake for 25-30 minutes until firm and golden.