Standard ratio (2 parts water to 1 part natural leaven)
Hoshino Natural Leaven (Tanzawa yeast)
50 g (100 g)
Lukewarm water (30℃)
100 g (200 g)
Your utensils and bowls should be sterilized by boiling them in hot water. You should also prepare a clean jar or container for storing the leaven. Measure out the ingredients and combine with a spatula or spoon.
At first, it should appear crumbly (with 50 g leaven and 75 g water.)
Wrap the jar in plastic wrap, secure with a rubber band, and poke 5-6 holes in the wrap with a toothpick.
After a full 24 hours at a room temperature of 25℃, it should smell fermented.
After a day and 1/2 or 2 days, the bubbles should reduce in size. If it tastes bitter like beer, it's done.
The starter can now be used, but it stabilizes better if left overnight in the refrigerator.
The completed starter will continue to ferment, so be sure to store it in the refrigerator. It should be used up within 2 weeks.
Here's a recipe for an oval-shaped pain de campagne (Recipe ID: 1812805). And one for a pain de campagne using Lys d'Or Campagne (Recipe ID: 1830356), which also uses a ratio of 1.5 times the amount of water to natural leaven.
Story Behind this Recipe
I learned that a certain famous bakery uses this ratio of 1.5 parts water to 1 part natural leaven, so I've been using that ratio ever since. Since I love the fragrance of Hoshino natural leaven, I use a ratio of 1.5 part water to 1 part leaven, which I think makes it more pronounced.
A ratio of 1.5 part water to 1 part leaven gives a more pronounced flavor and fragrance, and appears to also increase the shelf life of the yeast. The fermentation time is a bit longer than if using the standard ratio of 2 parts water to 1 part leaven. However, the process of making the starter is the same.