Bread yeast is used in baking to make dough rise. Without bread yeast, bread will not bake properly and will be flat in appearance. Bread yeast is available for purchase in many grocery stores. However, if you don't have any bread yeast at home or do not have access to purchase it, you can make the bread yeast yourself out of potatoes. This type of bread yeast will encourage the dough to rise and will produce similar results to store-bought bread yeast.
Pour 3 cups of water into a pot and bring to a boil.
Put 2 large potatoes into the boiling water for 30 minutes.
Remove the potatoes and let cool. This could take anywhere from 30 minutes to an hour.
Peel the potatoes with a potato peeler and mash the peeled potatoes in a bowl using a potato masher. You will no longer need the peels, so you can throw them away.
Add 1/4 cup of sugar, 2 tsp. of salt and 1 cup of warm water into the bowl with the mashed potatoes.
Stir the ingredients until they are completely mixed together and cover the bowl with a lid.
Put the bowl in a warm, dark place such as a kitchen cabinet and let sit for two days.
Remove the bowl after the second day and remove the lid. The contents will be fermented and smell slightly sour.
Use the yeast immediately or re-cover and place into the refrigerator until you are ready to use it. The yeast will remain fresh for about two months.
Two tbsp. of yeast made from potatoes is equal to 1 tbsp. of store-bought yeast.