Heat heavy large skillet over medium-low heat. Add pepitas. Cover and stir frequently until seeds puff and begin to pop, about 5 minutes (do not brown). Transfer to a plate and allow to cool for about 5 minutes.
Meanwhile, heat oil in heavy frying pan over medium heat. Add the chicken, allowing it to lightly brown on each side.
Pour the pumpkin seeds into a small food processor. Add the salsa and puree. Add salsa/pumpkin seed puree to the frying pan making sure to distribute the sauce over and under all pieces of chicken. Grind a little pepper over each chicken piece. Turn the heat down to simmer, cover, and cook gently for about 15 minutes until the chicken is thoroughly cooked.