Place all ingredients—the tomatoes, onion, brown sugar, granulated sugar, salt, coriander, cumin, cider vinegar, and lemon juice—into a dutch oven. Mix everything well to ensure even distribution of flavors.

Bring the mixture to a boil over medium-high heat. Once boiling, reduce the heat to medium-low, allowing the jam to simmer gently.

Cook the jam for at least three hours, stirring occasionally, until the mixture thickens and coats the back of a spoon.

Once thickened, process the jam in a hot water bath for canning or let it cool before transferring it to a container.