Purée the tomatoes in a food processor until smooth. Strain the purée, discarding the liquid. Set aside.
Heat the oil in a medium saucepan over medium-low heat. Add the onion and cook, stirring occasionally, until translucent. Add the. brown sugar; cook for 2 minutes. Stir in the tomato purée, chiles, cider vinegar, tomato paste, and coriander. Simmer until thickened, about 25 minutes. Taste and season to taste with salt and pepper; let cool.