In a pan, add chopped tomatoes, onions, garlic and ginger. Cook until soft and pulpy.
Let it cool slightly, then blend into a smooth puree.
Use a fine sieve to remove seeds and skin for a silky texture.
Pour the strained puree back into the pan. Simmer on medium heat to thicken slightly.
Stir in sugar, salt, vinegar, chili powder and spices. Cook until thick and glossy.
It should coat the back of a spoon. Adjust sweetness, salt or tang as needed.
Let it cool completely, then pour into sterilized glass bottles. Store in the fridge.