Day 1: Combine 50 grams of rye flour and 50 grams of lukewarm water in a glass jar. Cover loosely and let rest at warm room temperature (70-74°F) for 24 hours.
Day 2: Discard all but 50 grams of starter and feed with 50 grams of whole wheat flour and 50 grams of lukewarm water. Cover and let rest for 24 hours.
Day 3: By now you should be starting to see some little air bubbles and there should be a faint sour smell. You can now switch to feeding with all purpose flour if desired (if there are no bubbles, continue feeding with rye or whole wheat flour). Discard all but 50 grams of starter and feed with 50 grams of all purpose flour and 50 grams of lukewarm water. Cover and rest for 24 hours.
Day 4: By now there should be more bubbles and the starter should have nearly doubled in size. Repeat day 3's instructions.
Day 5: Your starter should be active with lots of bubbles and a strong sour smell. If so, you're ready to start using it! If not, keep repeating day 3's instructions for a few more days.
If you aren't seeing any bubbles after 5 days, don't get discouraged!! It can take up to two weeks to start seeing any activity with your starter. Just continue feeding and strengthening your starter. Even once your start is active, it can take several weeks to months to get a very strong starter that is ready to bake with consistently.
Once your starter is consistently active and doubling in size, you can use my beginner sourdough recipe to make your first loaf!