Day 1, On day 1, mix 50 grams of wheat flour and 50 grams of lukewarm water together. Place the mixture in a glass jar and loosely screw the lid on. Then, put an elastic band around the top of the jar. Move the rubber band every day to check if your starter is becoming active. Place the jar in a warm place in your home.*
Day 2, remove your starter from the jar and weigh out 50 grams of it, discarding the rest. * * Now add another 50 grams of wheat flour and 50 grams of lukewarm water. Mix together, put the mixture back in the jar, replace the rubber band and return it to the same place.
Days 3–7: Repeat Day 2. Your starter may rise and then collapse quickly again (this is why the rubber band is useful). It is definitely not ready yet, but your starter is starting to come to life. It's also fine if you see signs of life on day 3, but none at all on days 4 and 5. Be patient!
Day 8, if you notice that your starter rises well a few hours after feeding it every day, it may be ready. If not, simply repeat day 2. This process can sometimes take one week, two weeks or longer.
Day 9, check if your starter has doubled in volume within 8 hours of the last feeding. If so, it looks like your starter is ready. To be sure, put some water in a bowl and place a spoonful of starter on top (do not stir the starter beforehand!). Does the starter float? If so, you can start using your starter!
Good to know:
* Heat is important for activating the fermentation process, but it should not be too warm. So don't put your starter on the windowsill above the stove; put it in a warmer corner on a shelf instead. Avoid placing it on a countertop, as this can be a bit cold.* * When starting a starter, always discard part of the mixture. Please note that this is not sourdough residue or discard (you only get these from an active starter).