Fresh Tomato and Caramelized Onion Jam

Ingredients

• 3/4 pounds yellow onions, finely sliced
• 1 tablespoon butter
• 1 1/2 pounds roma tomatoes, peeled, cored, seeded, and finely chopped
• 1/2 cup white sugar
• 1/4 cup light brown sugar
• 2 tablespoons juice from 1 lemon
• 2 tablespoon apple cider vinegar
• 1 teaspoon kosher salt
• 1/2 teaspoon red pepper flakes

Directions

1. Set a large saucepan with a heavy base, either stainless steel or enameled cast iron, over high heat and melt the butter. Stir in the onions and cook them, moving them around often, until a light brown layer forms on the bottom of the pan, about 5 minutes. Pour in 2 tablespoons water and use a wooden spoon to loosen all that browned goodness. Keep cooking and stirring until the pan develops that browned coating again, about 2 minutes longer. Add 2 more tablespoons water and scrape the bottom clean. Keep repeating the same pattern of cooking, adding water, and scraping until the onions are fully soft and very dark brown, about 15 minutes total.
2. Add the tomatoes, white sugar, brown sugar, lemon juice, vinegar, salt, and red pepper flakes to the onions, then stir everything together. Let the mixture come to a boil, then lower the heat and let it simmer, stirring now and then, until the tomatoes collapse and the mixture thickens into a jammy texture, 1 to 1 1/2 hours.
3. Take the pan off the heat. Spoon the jam into an airtight container and refrigerate for up to 2 weeks, or ladle it into sterilized jars and process the jars in a hot water bath for 10 minutes to seal for self storage.