The chile Tuxtla is a small pequin chile from Southern Mexico. The chile gets its name from city, Tuxtla Gutierrez located in Chiapas, Mexico.
On a relative heat scale of 1 -10 this chile is about a 7. While this chile is mainly used in salsas it can also be added to soups or stews. It is pretty hot so start with a couple of chiles and add more to taste.
If you want to switch up the flavor try an alternative chile such as the small morita chipotle chile. The heat is moderate but it will add a nice smoky flavor.
Mark Miller - The Great Chile Book
Dave DeWitt - The Chile Pepper Encyclopedia