Pulse chillies & salt in a food processor and pulse until roughly chopped. Don't chop too finely or the fermentation weight will not be able to hold the pulp down.
Put the puree into a mason jar & put a fermentation weight on top. Make sure all the pulp is submerged.
Cap with a fermentation lid & airlock if your jar requires it. Set aside for 30 days in a cool dark place. Check it occasionally for any signs of contamination. It is normal to see bubbling & the airlock will move.
Add vinegar to contents & transfer to a large airtight jar. Set aside for a further 30 days & shake daily. The acidity from the vinegar & agitation will assist with breaking down the pulp, providing more depth & flavour to your hot sauce. Optional- use a stick blender to puree the contents for 60 seconds instead of shaking.
Blend mixture in a blender for 5 minutes.
Strain contents into a large pot using a fine-mesh sieve.
Heat the pot of sauce to 93 degrees (200F). Monitor with a thermometer. This will pasteurise the sauce without boiling it.
Fill a separate large pot 3/4 full of water. Heat to 74 degrees (165F) then place the empty glass sauce bottles & lids in it. Maintain this temperature & leave them in for 5 minutes to sterilise.
Remove sanitised bottles & lids from the water & fill with hot sauce. Quickly cap them then allow to cool to room temperature. If using mason or other jars with pressure-sealing lids, return them to the hot water for a further 5 minutes. Maintain a water temperature of 165F or 74C for the full 5 minutes.
Allow the bottles to cool to room temperature before applying a heat-shrink wrap.