vegetable oil, divided • medium onion, finely chopped (about 1 cup), divided • coriander seeds • cumin seeds • whole small dried red chile • whole black peppercorns • whole cloves • -inch piece of ginger, minced (about 1 tablespoon) • medium cloves garlic, minced (about 1 tablespoon) • fennel seeds • tomato purée • turmeric powder •