Day 1: Mix 15 grams white flour, 35 grams rye flour, and 50 grams water together. Let it sit in a closed container for 24 hours at room temperature.
Day 2,3,4,5: Feed with 25 grams white flour, 25 grams rye flour, and 50 grams water each day and keep it at room temperature.
Day 6: Remove 200 grams starter. Add 50 grams white flour, 50 grams rye flour, and 100 grams water. Leave at room temperature.
Day 7: The Starter should be nice and bubbly and ready to use. If you do not intend on baking straight away then move your starter to the fridge and feed once a week just like you did on day 2.
Video
Notes
Many elements play a part in fermentation. Your starter might take longer or less time than stated in the recipe.
You can use the sourdough discard for sourdough crêpes or simply freeze it for future use.
Discard some starter when it gets too sour and feed with 50/50 flour and water.