Preheat the oven to 350°F. Start combining the dry ingredients in a bowl.
Boil the cup of water and pour this into the bowl. Mix in the egg whites and vinegar as well. Beat the ingredients together with a hand mixer for around 30 seconds. Avoid overmixing. The outcome should have a Play Doh-like consistency.
Moisten your hands and shape the dough into 4-8 pieces. You can mold them into hamburger or hot dog buns, depending on your preference. Lay the formed dough on a baking sheet greased with oil.
Place the sheet on the lower rack of the oven and bake for 50-60 minutes. The time depends on the size of the bread you make. Check if done by tapping the base of the bun. If you hear a hollow sound, remove from the oven.
Serve together with some butter or your favorite toppings. Keep the bread in the fridge or freezer.