Preheat the oven to 300°F. Mix all the dry ingredients (almond flour, xanthan gum, baking powder and salt) in a bowl.
Add the hot water, the vinegar, and egg whites to the bowl. Mix with a hand mixer or your hands until all combined. Cool in the fridge for about 30 minutes.
Spray hands with coconut oil and form dough into 4 or 6 pieces of bread. You can also make hot dog or smaller slider buns. Place on a greased baking sheet, brush it with egg yolk and sprinkle with sesame seeds.
It must be baked on the lower rack of the oven for 50–60 minutes, depending on the size of your bread. Since this is a delicate bread, keep checking to make sure it is not browning too much on the outside or get burnt. You want to make sure it is cooked all the way.