Combine all of the ingredients in a heavy saucepot. Bring to a boil, then reduce to a simmer. Simmer uncovered for 30 minutes.
Let cool slightly and puree in a blender (preferred method) or a food processor. The ketchup will be smoother processed in a blender. If the ketchup seems too thin, place it back into the saucepot and reduce for a few minutes. Remember that the ketchup will thicken as it cools.
Refrigerate for future use or place in sterilized jars and process using traditional canning techniques.