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. Do not use overripe or spoiling tomatoes. The process of canning will not kill bacteria that may be present in tomatoes that are beyond ideal maturity.
Peppers range from mild to fiery in taste.
Choose a mild pepper when the recipe calls for long green chiles. You can substitute bell peppers for some or all of the long, green chilis. Canned chilis may be used in place of fresh. Use only high quality peppers. Do not increase the total amount of peppers in any recipe.