Heat a generous pour of olive oil in a sauté pan over medium heat. Add the onion and a pinch of salt, and sauté for 7 minutes, until translucent. Add the tomatoes, another pinch of salt and black pepper to taste. Keep sautéing for about 10 minutes, until the tomatoes begin to break down, then mix in the vinegar and sugar.
Keep cooking the vegetables over medium heat - everything in the pan should be gently simmering - for another 30-40 minutes, until all the liquid released by the tomatoes reduces. You should end up with a thick, jammy spread that's uniform and not liquidy. Taste for salt, sugar and acid and adjust if needed. Enjoy on toast with something creamy like nut cheese, topped with fresh basil, or however else you prefer! Keep refrigerated in an airtight container for up to a week.
Notes
We've been having so much fun experimenting with different types of tomatoes for this recipe. Sweeter ones, like the yellow Sungold variety, yield a very sweet jam and don't always require the full 2 tablespoons of sugar. Red tomatoes, on the other hand, are more savory and acidic, and do well with the full amount of sugar. This is why it's always good to taste your jam while it's cooking and adjust the flavoring according to your preference.
Recipe by Golubka Kitchen at https://golubkakitchen.com/savory-tomato-and-onion-jam/