3 Tablespoons Vegetable Oil
3 Cups Spanish Onion, Coarsely Chopped
3 Cloves Garlic, Thinly Sliced
3 28 Ounce Cans Plum Tomatoes, Drained and Coarsely Chopped
1/3 Cup White Distilled Vinegar
1/2 Cup Dark Corn Syrup
1/2 Teaspoon Ground Cloves
1/2 Teaspoon Ground Allspice
2 Teaspoon Yellow Mustard Seeds
½ Teaspoon Ground Celery Seeds
1 Tablespoon Coarse Sea Salt
2 Teaspoons Freshly Ground Black Pepper
In a large non-reactive stock pot or Dutch oven, heat the vegetable oil over medium high heat and cook the onion until slightly golden brown, stirring occasionally, about 8 to 10 minutes. Add the garlic and cook for another minute. Add the tomatoes, vinegar, corn syrup, cloves, allspice, mustard seeds, celery seeds, salt and pepper stirring to combine. Bring the mixture to a boil, reduce the heat and simmer, stirring occasionally for 1 hour. Pass the mixture through a food mill into a bowl and return the mixture to the pot. Bring the mixture back to a simmer and cook until very thick, stirring occasionally, about 45 minutes.
Remove from the heat and pour into sterilized jars if canning and continue to can as you normally would or pour into jars, cool completely at room temperature, cover with tight fitting lid and refrigerate for up to 1 month.