Makes 2 cups
Preparation time 75 minutes
- 2 1/4 lbs. plum tomatoes (about 6 to 8 large)
- 1 1/2 cups distilled white vinegar
- 2 1/2 tsp. coarse sea salt or kosher salt
- 1 cup sugar (or to taste)
- 1 tbs. grated onion or 1 tsp. onion powder
- 1/2 tsp. mustard powder
- 1/4 tsp. ground cinnamon
- 1/4 tsp. ground cloves
- 1/4 tsp. ground allspice
- 1/4 tsp. ground black pepper
- Bring a large pot of water to a boil. Add the tomatoes and cook until the skins break and the flesh becomes soft, five to 10 minutes.
- Drain the tomatoes and press through a fine-mesh food mill or sieve to remove the skins and seeds. Pour the sieved tomatoes into a medium-size saucepan. Add the vinegar and salt. Stir to combine.
- Bring the tomato mixture to a boil and then whisk in the sugar, onion, and spices. Return to a low boil, stirring occasionally, and cook about one hour until the mixture has reduced to one-fourth the original amount and thickened. Some tomatoes are more watery than others, so additional cooking might be necessary to reduce moisture.
- Your ketchup should be the consistency of tomato purée, slightly thinner than bottled ketchup; it will thicken when it cools. Pour into a sterilized jar. Cover and refrigerate for up to one month.
Note: A food mill separates these skins and seeds from the pulp, while a food processor chops and purées everything together. The biggest difference is texture; with a food mill you get a refined, smooth sauce, while a food processor turns out a slightly aerated, granular sauce. When it comes to ketchups, barbecue sauces, and fruit butters, you are better off using the food mill or a fine sieve.