Stir together the onion, celery stalks, olive oil, chili powder, paprika, cayenne pepper, ginger, garlic, and Italian seasoning in a large stock pot over medium-low heat. Let the vegetables sweat for 15 minutes.
Add the tomatoes and water to the stock pot. Bring the mixture to a boil and reduce to a simmer. Let simmer for 30 minutes, or until mixture has reduced.
Use an immersion blender or a blender in batches to puree the mixture until completely smooth. Push the mixture through a fine mesh strainer to remove any “pulp”, seeds, and chunks.
Pour the tomato mixture into a clean pot and add the apple cider vinegar and brown sugar. Bring to a boil and reduce to simmer. Let simmer for about 40 minutes, or until thick and the consistency of ketchup.
Pour into sanitized jars and seal tightly. Ketchup can last up to six months.