Zuurdesem, zonder de mythologie

Sourdough is bread leavened by a culture of wild yeast and lactic acid bacteria living in a flour-and-water starter, rather than by commercial yeast. It is slower, it keeps longer, and it is easier to digest. It is also surrounded by more folklore than any other thing made in a domestic kitchen.

Building a starter

Day one: mix 50 g wholemeal flour and 50 g water in a jar. Cover loosely.

Every day after: discard all but 50 g, then feed 50 g flour and 50 g water. Same time each day.

Expect: nothing for two days, alarming activity around day three or four (this is usually the wrong bacteria and passes), a quiet lull, then steady rising and falling by day seven to ten.

It is ready when it reliably doubles within 4 to 6 hours of feeding and smells of yoghurt and apples rather than acetone or drains.

The discard is not waste — it goes into pancakes, crackers or flatbreads.

The loaf

For one loaf, around 900 g:

Ingredient	Weight	Baker's %
Strong white flour	400 g	80%
Wholemeal flour	100 g	20%
Water	375 g	75%
Active starter	100 g	20%
Salt	10 g	2%

Start with 70% hydration if you are new. Wet dough tastes better and handles worse; there is no honour in fighting a 85% dough into a puddle.

Schedule

1. Autolyse — mix flours and water only. Rest 45 minutes. This hydrates the flour and starts gluten forming without any work from you.
2. Mix in starter and salt. Squeeze through until fully combined.
3. Bulk ferment, 4–6 hours at 22 °C. In the first two hours, perform four sets of stretch-and-folds thirty minutes apart: wet hand, lift one side of the dough, fold it over, rotate the bowl, repeat four times.
4. Judge by the dough, not the clock. Bulk is done when it has risen 50–75%, feels airy, and shows bubbles at the surface and edges. Warm kitchen: faster. Cold kitchen: much slower.
5. Pre-shape, rest 20 minutes uncovered, then shape with tension and place seam-up in a floured banneton or a cloth-lined bowl.
6. Cold proof in the fridge, 12–16 hours. This is where the flavour is made, and it makes the dough far easier to score.

Baking

Bake straight from the fridge.

• Preheat a Dutch oven at 250 °C for 45 minutes.
• Turn the loaf out, score once, decisively, at a shallow angle.
• 20 minutes lid on at 250 °C — the trapped steam gives you the rise and the blistered crust.
• 20–25 minutes lid off at 220 °C, until deep brown. Pale bread is under-baked bread.
• Cool at least two hours before cutting. The crumb is still setting; cutting early makes it gummy, and it is not the recipe's fault.

Reading the crumb

• Dense and tight — under-fermented, or a weak starter. Longer bulk, or feed the starter more often before baking.
• Gummy and collapsing — over-fermented. Shorter bulk.
• One large tunnel under the crust — shaping was too loose.
• Flat and spreading — over-proofed, under-shaped, or hydration beyond your current handling.

Why keep one

A starter costs a spoonful of flour a day and turns three ingredients into bread that stays good for most of a week. There is no packaging, no yeast to buy, and the schedule bends around a working day rather than the other way round. The mythology is optional. The method is not.