Step 1Heat the oil in a large, wide, deep pan over medium-low heat. Add the green, red and yellow bell peppers and cook them until softened, 10 minutes. Remove the peppers with a slotted spoon. Add the tomatoes to the pan, sprinkle them with salt and cook over high heat until they begin to boil. Cook uncovered over medium heat, stirring occasionally, for 20 minutes.
Step 2Return the peppers to the pan and add the garlic, jalapenos, cumin and paprika. Cook over medium heat, stirring often, until the bell peppers are tender and the sauce is thick, 10 minutes. Add half the cilantro and cook for 2 minutes. Taste and adjust the seasoning, adding cayenne if you like. Stir in the remaining cilantro. Serve hot, cold or at room temperature.
Step 3Stir before serving.