Step 1

In a 5- to 6-quart pot, combine the sugar, vinegar, and 1/4 cup water. Cook over medium heat, stirring occasionally, until the sugar dissolves and the mixture looks syrupy, about 5 minutes.

Step 2

Add the tomatoes, red pepper flakes (if using), and 1/2 tsp. salt.

Step 3

Cook over low heat, stirring occasionally, until the tomatoes have broken down and the juice has thickened, 1-1/2 to 2 hours. (You may need to stir more frequently as the jam thickens.)

Step 4

Season to taste with salt. Let cool to room temperature, transfer to a jar, and refrigerate for up to 2 months.

Step 5

For more ideas, see “Twelve Ways to Use Tomato Jam.”