Making your own ketchup is very satisfying, not only because the flavor is fresher and deeper but also because it gets that way with far less sugar and salt and no preservatives or artificial flavors.
If using homegrown tomatoes instead of canned crushed tomatoes, core and quarter them and then simmer them in a heavy saucepan until thickened (about 30 to 45 minutes). Put through a strainer and then proceed with the following recipe.
28-ounce can crushed tomatoes (or 12-15 medium tomatoes)
1 small yellow onion, chopped
½ cup apple cider vinegar
¼ cup light agave syrup
2-inch piece of fresh ginger root, peeled and chopped
1 teaspoon celery salt
1 clove garlic
½ teaspoon freshly ground black pepper
½ teaspoon dried thyme
¼ teaspoon ground cinnamon
¼ teaspoon ground allspice
1/8 teaspoon ground cloves
Combine all ingredients in a food processor and process until smooth. Transfer the mixture into a saucepan and bring to the boil. Reduce heat and simmer until reduced by half, about 25 to 30 minutes. Remove from heat and let cool. Pour into clean, half-pint mason jars. Store in the refrigerator and use within 30 days. Makes three half-pints.
Note: The jars can also be processed in a water bath for 10 minutes to seal the lids. The ketchup can also be frozen in a freezer-safe container for future use.