Smoky blackberry ketchup

Method

1. Wash the blackberries in a colander under a cold tap, then shake off as much water as you can. Tip them into a large heavy-based stainless-steel (non-reactive) pan or preserving pan with a lid.
2. Grind the celery seeds, juniper and peppercorns finely using a spice mill or a pestle and mortar. Put everything but the sugar into the pan with the blackberries and put over a low-medium heat.
3. Bring the mixture up to a simmer (it should bubble gently), cover with the lid and cook for 30-40 minutes or until everything is very soft. Remember to stir from time to time to prevent the mixture from catching and burning on the base of the pan. Remove from the heat and leave for 5 minutes (blending super-hot mixtures can be explosive).
4. Once the mixture has cooled a bit, spoon it into a blender, take out the central stopper, cover the hole with a tea towel, then whizz until smooth (you may need to do this in batches). Put a sieve over a glass bowl and, using a wooden spoon, rub the mix through it until only a dry, fibrous residue is left in the sieve (discard).
5. Return the sauce to the washed pan and add the sugar, stirring it in well. Put the pan over a low heat and stir until the sugar has completely dissolved; there should be no grittiness left in the pan.
6. Simmer the ketchup over a medium heat until thick (about 15 minutes), stirring often as it has a tendency to stick to the bottom of the pan at this stage. Once it’s as thick as you wish (remember it will thicken more as it cools), remove from the heat and set aside for 5 minutes.
7. Stir once more, then pot into the still-hot sterilised jars or bottles. Seal with vinegar-proof lids and leave to cool. Once cold, label the ketchup and check the lids are tight. Store in a cool dark place.