Place 6 clean 250 ml mason jars on a rack in a boiling-water canner, cover with water, and heat to a simmer at 180°F (82°C). Keep jars hot until ready to fill.

Wash lids in hot soapy water, dry, and set aside at room temperature.

Wear gloves. Remove pepper stems and chop the peppers. For a milder sauce, remove the seeds and white membranes.

Combine vinegar and sugar in a large stainless-steel saucepan. Bring to a boil over high heat, stirring occasionally; reduce heat and simmer 3 minutes.

Add peppers, sultanas, garlic, gingerroot, and salt. Return to a boil, reduce heat, and simmer 5 minutes. Remove from heat.

Ladle sauce into a hot jar, leaving a 1/2-inch headspace. Remove air bubbles, adjust headspace with more sauce if required, wipe the rim, apply the lid and band fingertip-tight, and return the jar to the canner. Repeat.

Ensure jars are covered by at least 1 inch (2.5 cm) of water. Cover the canner and bring to a full rolling boil. At altitudes up to 1,000 ft (305 m), process for 10 minutes.

When processing is complete, remove the canner lid and wait 5 minutes. Remove jars upright and cool undisturbed for 24 hours; do not retighten bands.

Check seals, remove bands, wipe and dry jars and bands, label, and store in a cool, dark place. For best quality, use within one year.