Ingredients :

• Roma or San Marzano Tomatoes (7 kg) — These are really what you need. Fleshy, not very juicy, their flesh holds up during cooking without releasing water everywhere. If you use vine tomatoes or classic round ones, your purée will be too liquid and you’ll have to cook it twice as long to reduce it. In mid-summer at the market, Roma tomatoes are often cheaper—it’s the right time to buy them in bulk.
• Fresh basil — No dried basil here, it adds nothing. A few whole leaves in each jar, slipped in just before closing. The infusion happens slowly during storage—upon opening months later, the fragrance is there, discreet but very present.
• Jars with seals (Le Parfait or Mason jar type) — Check the condition of the rubber seal before each use—if it’s cracked or slightly deformed, it won’t create the vacuum correctly and your preserve won’t keep. A new seal costs a few cents and prevents losing all your hard work.