In a bowl, add 100 g flour, pour in 100 ml water and mix well with a fork. Cover the bowl with a towel and leave for 24 hours in a warm spot away from drafts.

Small bubbles and a slightly sour smell will appear on the starter. Feed it: add another 100 g flour and 100 ml water, and stir until it's the consistency of thick sour cream.

Cover with a towel and leave for 24 hours in a warm place, stirring it about three times during this time.

The starter should be bubbly and topped with a foamy cap, with a pleasant sour or even quite sharp smell - that's normal.

Feed it once more: 100 g flour and 100 ml water, stir and leave in a warm place.

The starter is ready: you can take out some for baking bread, and in return add back the same amount of flour and water, leave it in a warm spot, then refrigerate.