Place 5 clean 500 ml mason jars on a rack in a boiling water canner. Cover jars with water and heat to a simmer (180°F/82°C). Set screw bands aside. Keep jars hot until ready to use.

Blanch, peel, seed and coarsely chop tomatoes. Measure 7 cups (1750 ml). Wearing rubber gloves remove seeds and finely chop jalapeño.

Combine tomatoes, onions, green pepper, jalapeño pepper, garlic, tomato paste, vinegar, cilantro and cumin in a large stainless steel saucepan. Bring to a boil; boil gently, stirring occasionally, until salsa reaches desired consistency, about 30 minutes.

Ladle salsa into a hot jar to within ½ inch (1 cm) of top rim (headspace). Using nonmetallic utensil, remove air bubbles and adjust headspace, if required, by adding more salsa. Wipe jar rim removing any food residue.

Centre hot sealing disc on clean jar rim. Screw band down until resistance is met, then increase to fingertip tight. Return filled jar to rack in canner. Repeat for remaining salsa.

When canner is filled, ensure that all jars are covered by at least one inch (2.5 cm) of water. Cover canner and bring water to full rolling boil before starting to count processing time. At altitudes up to 1000 ft (305 m), process – boil filled jars – 20 minutes.

When processing time is complete, remove canner lid, wait 5 minutes, then remove jars without tilting and place them upright on a protected work surface. Cool upright, undisturbed 24 hours; DO NOT RETIGHTEN screw bands.

After cooling check jar seals. Sealed discs curve downward and do not move when pressed. Remove screw bands; wipe and dry bands and jars. Store screw bands separately or replace loosely on jars, as desired. Label and store jars in a cool, dark place. For best quality, use home canned foods within one year.