**Prepare the Tomatoes:** Begin by washing your tomatoes thoroughly. To transform them into juice, core and quarter the tomatoes, then simmer them in a large pot until they soften. Use a food mill or a strainer to remove the skins and seeds, ensuring a smooth juice.

**Reduce the Juice:** Pour the strained tomato juice into a large pot and bring it to a gentle boil. Lower the heat and let it simmer for several hours, stirring occasionally. Your goal is to reduce the juice by about half, creating a thick, paste-like consistency.

**Season the Ketchup:** Once the juice has thickened, add the vinegar, sugar, salt, onion powder, cinnamon, ground cloves, all-spice, and cayenne pepper. Stir the mixture and continue to simmer for an additional 30 minutes, allowing the flavors to meld and intensify.

**Adjust the Flavor:** Taste your ketchup and tweak the seasoning to your liking. If you prefer a sweeter profile, a little extra sugar can be added. For more heat, increase the cayenne pepper slightly.

**Store Your Creation:** Once your ketchup has reached the desired taste and consistency, remove it from the heat. If you plan to store it for an extended period, consider using sterilized jars and a proper canning process. Otherwise, let it cool and keep it refrigerated.