Heat the oil in a large heavy bottom pan and gently fry the onions and garlic for 10 minutes, or until softened and tingeing caramel coloured.
Add the celery, chilli, horseradish, coriander, ginger, allspice, cayenne, cloves, tomatoes and puree. Bring to boil, then reduce the heat and simmer for thirty minutes or until it has reduced the amount of liquid in the pan by half.
Stir in the vinegar, salt, sugar, pepper, Worcestershire sauce, hot sauce, lemon juice and celery salt. Stir continually and boil for 10 more minutes.
Transfer the mixture to a liquidizer and blend until smooth. Pass the mixture through a very fine sieve into a clean pan and bring to the boil. Boil for about 5-10 minutes or until the sauce is thickened bearing in mind it will thicken slightly as it cools. Set aside to cool slightly. Transfer through a sterilized funnel into sterilized bottles.
Yield 4-5 bottles.
Recipe courtesy of Gizzi Erskine.