More salsa is sold today than ketchup or other tomato-based sauces.
Most salsa recipes are a mixture of low-acid foods, such as onions and peppers, along with acid foods, such as tomatoes. If you are developing your own recipe, it must be frozen. The type of tomato used often affects the quality of salsas. Although both types make good salsas, paste tomatoes such as Roma have firmer flesh and produce thicker salsas than large slicing tomatoes, which tend to yield a thinner, more watery salsa. Salsa can be thickened by adding tomato paste.