Sourdough, step by step

1. Equipment and a warm spot

A starter needs flour, water, a jar and a scale, nothing you have to buy in a special shop.

1. Jar and rubber band — A glass jar, 0.7–1 L, with a wide neck and a lid that doesn't seal tight. A rubber band marks the level after feeding.
2. Scale to 1 g — Ratios go by weight, not by cups. The scale is the most important tool.
3. Flour and water — To start, wholemeal rye or wheat flour. Water without chlorine: well or spring water, or tap water left standing for 12 h.
4. A warm spot — Best at 24–26 °C (75–79 °F), near the range or Aga, but not on it. At 18–20 °C (64–68 °F) a starter works half as fast, but it works.

Why: Wild yeasts and lactic acid bacteria live in a starter. The yeasts raise the dough, and the acid gives flavour and protects the bread from mould. Warmth and exact ratios decide how fast they work.

• Leave tap water open for 12 h so the chlorine evaporates, because chlorine slows the culture. If your water company uses chloramine, standing doesn't help: use a carbon filter jug or bottled spring water.
• A switched-off oven with the light on is often 28–32 °C (82–90 °F): check with a thermometer and leave the door ajar.

2. The starter day by day

From the first spoonful of flour to the first loaf takes 7–14 days.

1. Day 1 — Mix 50 g of wholemeal flour with 50 g of lukewarm water (26–28 °C / 79–82 °F) and cover loosely. A thick paste; nothing happens.
2. Days 2 and 3 — On day 2 add 50 g of flour and 50 g of water: it often foams and rises. On day 3 it goes quiet: that's normal.
3. Discard goes in the bin — From day 3 keep 50 g, take the rest out, then feed 50 g of flour and 50 g of water. What you take out on days 3–7 goes in the bin or the compost.
4. Twice a day — From day 5 feed 50 + 50 g every 12 hours. Carry on until it doubles in volume in 4–8 hours, three times in a row.

Why: In the first days, bacteria that are not the true residents of the starter are also at work. As the acid rises they disappear, and the yeasts and lactic acid bacteria take over.

• Don't give up on day 3, and don't change flour halfway.
• If nothing happens even on day 7, move the jar somewhere warmer.

3. When the starter is ready · Locked

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4. Feeding and the fridge · Locked

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5. A dried backup · Locked

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6. The levain and the discard · Locked

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