For the Mexican sauce, finely chop the garlic and onion. Sauté in oil for a few minutes until translucent.
Add coriander, cumin and oregano and continue to cook, stirring, for 2 minutes.
Remove seeds from chili peppers, chop finely and add to sauce with remaining ingredients.
Puree tomatoes, add, reduce heat and simmer for 20 minutes, stirring frequently, until sauce thickens.
Allow to cool and cover the Mexican sauce to chill.