Day 1: In a medium-sized glass bowl, mix together 50 grams of filtered water and 50 grams of white all-purpose flour. Stir well until there are no lumps left, then cover the bowl and let it sit at room temperature for 24 hours.
Day 2: To yesterday’s mixture, add another 50 grams of flour and 50 grams of water. Stir until the mixture is smooth, cover it again, and let it sit out at room temperature.
Day 3: Discard half of your established starter. Add 100 grams of flour and 100 grams of water to the remaining mixture, stir well, and cover. Allow it to sit at room temperature once more.
Day 4: Throw away half of the starter. To the remaining half, add 150 grams of flour and 150 grams of water. Mix thoroughly, cover, and let it rest at room temperature.
Day 5: Discard half of your starter again, leaving room for 150 grams of flour and 150 grams of water to be added. Stir well, cover, and let it sit at room temperature.
Day 6: Once more, discard half of the starter. Add 200 grams each of flour and water, mixing well. Cover it, leaving it at room temperature to ferment.
Day 7: Check if the starter looks ready. If it resembles a bubbly and slightly sour consistency, it's ready to use. If not, it may need another day of feeding and resting.