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Blitz the onion, garlic and chillies together in a food processor until you&rsquo;ve got a really fine paste. Pour a lug of olive oil into a pan and gently fry this paste for 5 minutes on a low heat to really get the flavours going.<br />
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While that&rsquo;s happening, add all your herbs and spices to the food processor, then peel in strips of orange zest using a speed peeler (you don&rsquo;t want any white pith) and blitz up really well. Add this pur&eacute;ed mixture to the pan and cook for another minute. Add the sugar, stir in well and cook for a few more minutes, until it begins to dissolve and you get a thick brown paste. Pour in 285ml of water and cook for 2 more minutes, then squeeze in the juice of both your oranges and add all the remaining ingredients. Stir well and bring everything to the boil, then turn down the heat a touch and simmer for 5 to 10 minutes, until the mixture starts to thicken slightly.<br />
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Pour the sauce slowly through a fine sieve into a large bowl and get rid of any larger bits left behind in the sieve. Rinse the sieve and pass the sauce through the sieve again so it&rsquo;s really silky.<br />
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Leave to cool completely, then either divide the sauce between jars or get marinating straight away. Once it&rsquo;s in the fridge, you&rsquo;ll have about a week or so to use up the rest of the sauce. If you want to keep it for longer, you&rsquo;ll have to sterilize some jars. It&rsquo;s dead easy. Either put them in the sink along with their lids and cover them completely with boiling water from the kettle; or fill a really large pan with water, bring it to the boil, then immerse the jars and lids and continue to boil for 10 minutes; or, if you&rsquo;ve got a good dishwasher with a really hot cycle, run them through that.<br />
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Pour the sauce into your sterilized jar, screw the lid on tightly, and immerse the jar completely in a pan of boiling water for 10 minutes. Let it cool, then put it into the fridge or a cool dark cupboard until you need it. It should keep for about 6 months, no problem</p>