Set grill to high. Brush tomato halves with 1 tablespoon of olive oil and sprinkle with 1 teaspoon of garlic. Place tomatoes and onion quarters cut side down on hot grill. Cook, turning occasionally until lightly charred on all sides. Remove and cool slightly, then roughly chop onions.
Heat remaining tablespoon of oil in a saucepan over medium low heat. Add charred onion and celery and cook until softened. Add charred tomato, vinegar, sugar, tomato puree, salt, remaining teaspoon garlic, allspice, thyme and smoked paprika. Stir until well mixed. Bring to a boil and reduce heat to low and cook for 40 minutes.
Cool slightly. Transfer to a blender and blend until smooth. Refrigerate until needed.
This is a perfect house made condiment for any bar or pub snack, but delicious with our Carrot Hot Dog recipe.