Tomato Ginger Jam

In a large saucepan over medium-low heat, add oil and red onion. Cook onions for 5 minutes, until soft, stirring often. Add ginger and cook another 2 minutes. You want the onions to be completely soft before you add the tomatoes, but not brown at all—that will change the color of the jam. Add fresh tomatoes and cook over medium heat for 8 minutes, stirring often. Add sugar and vinegar and a pinch of cinnamon and red pepper flakes (optional). Cook over medium-low heat for 10 minutes, stirring often. Remove pan from heat and season to taste with kosher salt. Transfer to a bowl and let cool.