1. Wash tomatoes thoroughly under cool water. Place them on a dry cloth, pat gently to dry, then cut into quarters.
2. Heat olive oil in a very large pot. Add onions and cook for 4–5 minutes. Add garlic. Cook for 1 minute.
3. Add quartered tomatoes, bay leaves, basil sprigs, salt, sugar and pepper.
4. Slowly bring to a boil. Cook and let reduce by half over 2–3 hours. Remove from heat. Let cool.
5. Strain sauce through a fine-mesh strainer to remove tomato skins and seeds. Lightly mash to recover as much sauce as possible. Add recovered sauce back into the pot. Slowly bring to a boil. Add salt and sugar to taste. Cook for 5 minutes.
6. While sauce heats up, put jars, lids and rings in a large pot of boiling water for 10 minutes. Remove sterilized jars from water using tongs. Place them on a clean work surface. Set pot of boiling water aside.
7. Add 15 mL (1 tbsp.) of lemon juice to each jar. Fill jars immediately with hot sauce, while they’re still hot.
8. Sterilize a butter knife by boiling it in water for 10 minutes and let it cool. Use it to remove air bubbles from the jars by gently stirring their contents using the knife. Keep jars covered to prevent contamination.
9. Still using tongs, place lids on top of jars. Add rings, then tighten until you feel resistance.
10. Put jars back in the pot. The water should cover the jars by 2.5 to 5 cm (1 to 2 inches). Cook for 40–45 minutes.
11. Turn heat off and let jars rest in the water for 15–20 minutes.
12. Place a dry cloth on a work surface. Using tongs, remove jars from water and put them on the cloth. Let cool for 12–24 hours.
13. Label and date jars. Store in a dark and cool place. Keeps for 12–18 months.

Chef’s Secret 

• Use a funnel to keep everything clean and sterile. Do not touch anything with your hands.