Homemade ketchup is a great way to use up an excess of fresh tomatoes. It keeps, covered, in the refrigerator for two to three months.
Makes about 1 quart
Place the chopped tomatoes and onion in a heavy pan. Simmer until soft (about 30 minutes). Place a colander over a large bowl. Put the tomato mixture in the colander and press through as much liquid into the bowl as possible. Return the liquid your original pan. Add the remaining ingredients. Simmer for about 2 hours (or until thickened). Allow to cool slightly. Refrigerate.