Fire roasted tomatoes are exactly as they sound, charred tomatoes over an open flame. Which are then diced and canned. Fire roasted tomatoes give any dish a nice smokey flavor. A great addition to any salsa, soup or sauce.
Cornstarch is a flour derived from corn, and used as a thickening agent in liquid based foods, as well things like gloves, and baby powder. Cornstarch is used in replacement of a roux to make recipes gluten-free.