Combine all the ingredients in a pot over medium heat. Cook over medium heat for 75 minutes. Taste and adjust seasoning.
Your jam is ready when it coats the back of a serving spoon like a thick, viscous consistency!
Notes
Types of tomatoes: Try to use fresh garden tomatoes (I used a combination of Sungold cherry tomatoes and some vine tomatoes). Roma tomatoes are also excellent, but make sure to core large tomatoes (otherwise it gets watery!)
Reducing amount of sugar: I use 2/3rds cup of sugar. I find that reducing it more than that makes the jam taste like marinara.
Adjust seasoning: I use simple seasoning here, but you can also add star anise, cloves, cinnamon, and any other warm spices.
Thickening the jam: You ideally want all the extra water to evaporate and for the tomatoes to cook down to a thick consistency that coats the back of your spoon. The jam does thicken after you take it off the heat!
Skin versus no skin: I like leaving the skins on because it's easier that way but if you don't like the texture of the skin you can remove it two ways: either freeze the tomatoes and then thaw them (the skin slides right off) or you can boil and then remove the skins.