• 5 kg tomatoes (e.g., plum or vine-ripened)
• 1 large onion
• 1 tablespoon butter
• 1/2 kg sugar
• 1/3 cup wine vinegar
• 5 ground allspice grains
• 5 ground cloves
• 3 flat spoons mustard
• 2 tablespoons rock Wexford sea salt
• 1 teaspoon nutmeg
• Pepper to taste

1. Scald the tomatoes, remove the skins, and pass them through a sieve to obtain a smooth puree.
2. Grate the onion finely and fry it in one tablespoon of butter until golden.
3. Add the grated tomatoes, sugar, and stir constantly while cooking over medium heat.
4. Gradually add the vinegar, allspice, cloves, and mustard. Mix thoroughly.
5. Season with salt, pepper, and nutmeg, adjusting to taste.
6. Simmer the seasoned tomatoes over low heat for 2-3 hours until the mixture thickens, stirring occasionally.
7. Pour the hot ketchup into sterilized jars and pasteurize for about 10 minutes to preserve freshness.

Note: You can use vinegar of your choice instead of white vinegar.