1. Bring a large stock pot of water to boil, and blanch the tomatoes a few at a time, until the peel loosens (about 1 min). Transfer immediately to an ice bath to cool, and peel carefully. Remove the cores and dice.
2. Place the diced tomatoes in a large sauce pan with the rest of the ingredients, and stir to combine. Bring the mixture to a simmer over medium-high heat, then reduce the temperature to medium, keeping a slow simmer going.
3. Cook for 1-2 hours, stirring occasionally and adjusting heat as needed, until the mixture is thick and syrupy. Remove from heat and transfer to a container to cool.
4. Serve at room temperature, or store in an airtight container and refrigerate for up to 3 days.