In a large, heavy saucepan heat the olive oil over medium heat. Add the onion and bell pepper and saute for 5 minutes, or until tender. Add the jalapeno, garlic, cumin, coriander, salt, pepper and saute for another 2 minutes. Stir in the tomato paste and cook for an additional 2 minutes, stirring frequently.
Add the tomatoes with their juices and the vegetable stock. Raise the heat to high and bring to a boil. Decrease the heat to medium-low, cover, and simmer for 30 minutes, stirring occasionally until all of the vegetables are very tender and the liquid has reduced slightly.
Use a handheld immersion blender to puree the sauce until completely smooth. Alternatively, let the sauce cool slightly and puree in a high powered blender until smooth. Add the cilantro and continue to blend until the cilantro is finely chopped. Season to taste with more salt and pepper if desired.
To store: Allow the sauce to cool completely then store covered tightly in the refrigerator for 2-3 days
