In a saucepan, combine tomatoes, onion, garlic, and ginger. Cook over medium heat until softened.

Add brown sugar, vinegar, cumin, coriander, salt, and pepper. Stir well and bring to a boil.

Reduce heat and simmer for 30 minutes, stirring occasionally until thickened.

Remove from heat and let cool. Blend to desired consistency.

Store in sterilized jars and refrigerate.