Heat the olive oil in a medium-sized saucepan over a low-medium heat. Add the onion and the salt, stir well and drop the heat to low. Continue cooking for about 8 minutes, stirring occasionally so the onions gently soften but get nowhere near to browning. Stir in the garlic and cook for another 90 seconds. Good.
Add the chopped cherry tomatoes and the diced chiliEs, turn the heat to medium, give everything a good stir and after two minutes – plus a couple more stirs - drop the heat to low again. Cook for about 12 minutes with a couple of encouraging stirs so the tomatoes give up most of their body.
Now add the ginger, cumin, paprika, fish sauce, and black pepper. Stir well to combine everything. Turn the heat to medium, bring the pan to a bare boil, and then immediately remove it from the heat.
Let the mix cool for a few minutes, then pour it into a food processor. Whizz it for a minute, then return it to the pan set on a low-medium heat. Add the demerara sugar and give the pan a thorough stir. As soon as the jelly starts to bubble, lower the heat and let it gently – and I mean gently - simmer for 35 minutes, stirring now and again to prevent any sticking to the bottom or sides of the pan.
Remove the pan from the heat and then stir in the lime juice. Set the pan aside with the lid ajar, and let it cool for 15 minutes. That’s it, chili jelly done.
While the jelly’s cooling, you can prep its jar. Thoroughly wash and rinse the jar and its lid in hot water. Dry the lid and shake most of the water from the jar before setting it in a microwave for 2 minutes on high. This will pretty much sterilize the jar. Take a bit of care now – that jar’s gonna be hot when you remove it from the microwave.
Pour the chili jelly into the jar and lightly screw on the lid – don’t screw it fully closed – and let the jar cool for 30 minutes before you tighten the lid.