Prepare the Ingredients: Peel and chop the tomatoes. Optionally, blanch them in boiling water for a minute, then transfer to ice water to peel the skin easily. Finely chop the onions, bell pepper, and garlic.
Cook the Vegetables: In a large pot, heat the vegetable oil over medium heat. Add the onions and bell pepper. Sauté for 5-7 minutes until softened. Add the garlic and cook for another minute.
Add Tomatoes and Spices: Stir in the chopped tomatoes, followed by sugar, salt, mustard seeds, allspice, ginger, turmeric, and black pepper. Stir to combine, then cook on medium-low heat for 30 minutes, stirring occasionally.
Add Vinegar and Worcestershire Sauce: Pour in the Worcestershire sauce, white vinegar, and apple cider vinegar. Let the mixture simmer for another 40-60 minutes, stirring occasionally until it thickens to your desired consistency.
Blend (Optional): If you prefer a smoother relish, use an immersion blender or regular blender to blend until smooth. Otherwise, leave it chunky for a rustic texture.
Cool and Store: Allow the relish to cool before transferring it to sterilized jars. Seal tightly and store in the refrigerator for up to 2-3 weeks.
