makes a heaping cup of conserva; divide into two jars each with 6–8 ounce capacity; keep refrigerated; adapted from Alice Waters, The Art of Simple Food II
For larger tomatoes, cut around the stem end and transfer to large heavy pot or dutch oven (approx 5 quart capacity). For cherry tomatoes, cut in half.
Add olive oil and salt and bring to boil over medium-high heat. Reduce heat to simmer 5 minutes, stirring once or twice, then remove from heat.
Pass the tomatoes through a food mill with a fine plate to remove the seeds and skin or use a chinoise and pestle. (This is not the time for a blender or food processor unless you remove the tomato skins and seeds before cooking, which is a big pain.)
Preheat oven to 300°F. Transfer the tomato purée to a 9- by 13-inch non metallic baking dish, like a Pyrex lasagne dish. Bake for 3–5 hours, stirring every 30 minutes until brick red, very thick, and reduced to about a heaping cup. If edges begin to get too dark, reduce heat to 250°F.
Sterilize two half-pint jars (or Weck mold jar 976, pictured, which holds 5.6 ounces) and lids by boiling in water for 10 minutes. Sterilize a spoon, funnel, and table knife as well. Transfer the finished conserva into sterilized jars. Using the table knife, cut through the conserva to remove air pockets and smooth top. Pour in ½-inch of olive oil. Seal with lids, cool to room temperature, then place in refrigerator.
Always use a clean spoon to dip in and use the conserva. Add additional olive oil to keep conserva covered by ½-inch of oil. Keep refrigerated. Should last for months.
Keep watch for white mold. If you see it, discard the conserva as it has become contaminated by sloppy handling, unclean spoons, malfunctioning refrigerator (this happened to me one year, so sad!), or not using enough oil to form a barrier.