Sir torshi

Step 1: Wash a 1-litre glass jar and its lid in hot soapy water, rinse and dry it in a 250°F oven for 15 minutes. Let it cool. Use a plastic-lined or glass lid; vinegar eats through bare metal.

Step 2: Peel only the loose, papery outer layers from the 10 whole garlic heads, leaving each head whole and the cloves still wrapped in their inner skins. Trim the root hairs and any long stem. Common mistake: peeling down to the cloves, which then fall apart and turn mushy.

Step 3: Pack the heads snugly into the jar. Stir the 1 tbsp fine sea salt and 1 tbsp date syrup, if using, into the 3 cups white grape vinegar or cider vinegar (at least 5% acidity) until dissolved and pour it over so the garlic is covered by at least 2 cm.

Step 4: Close the jar and keep it in a cool, dark cupboard. For the first week the vinegar may cloud and the cloves may turn blue-green; this is harmless and fades. Top up with vinegar if the level drops below the garlic.

Step 5: Leave for at least 3 months, better 6 to 12. It is ready when the cloves are light brown to dark amber all the way through and squash easily between your fingers, with a sweet, mellow taste. Always lift cloves out with a clean, dry spoon, and never store garlic in oil instead of vinegar.