In a medium saucepan warm the beef broth.
Split and deseed dried chiles.
Toast chiles in a cast iron pan for approximately 20-30 seconds per side. Chiles will begin to have a fruity smell and darken, resembling leather. Be careful not to over-toast.
Tear or cut chiles into 1-2 inch pieces and add chiles to broth. Bring to a boil and then remove from heat, letting sit for 5-10 minutes.
Blend chiles and beef broth in a blender for approximately 2-3 minutes or until chiles have been broken down. Add tomato paste and then blend until smooth.
Using a spatula work the chile mixture through a wire strainer to remove residual chile stems or seeds.