Heat the oil in a pan.

Lightly toast the ancho chiles and remove them from the oil.

In the same oil, add the onion, garlic, sesame seeds, peanuts, and pumpkin seeds. Toast until everything is slightly browned, then add the tomatoes.

Add the chiles to the mixture, pour in the chicken broth, and let it simmer a bit. Blend everything very well in a blender.

If desired, strain the mixture, although it's not necessary if everything is well blended; this way, it remains thicker.

Return the mixture to the pan and let it simmer for a while until it thickens slightly, stirring constantly with a wooden spatula.