In a large pot or Dutch oven, heat the vegetable oil over medium heat. Add the chopped onion and garlic and cook until softened and fragrant, about 3-4 minutes.

Add the chicken pieces to the pot and cook until lightly browned on all sides, about 5-6 minutes.

Stir in the chopped tomatoes, bell pepper, carrot, and potato. Cook for another 5 minutes, stirring occasionally.

In a separate dry skillet, toast the sesame seeds and pumpkin seeds over medium heat until lightly browned and fragrant, about 2-3 minutes. Remove from heat and let them cool slightly.

In a blender or food processor, combine the toasted sesame seeds, pumpkin seeds, toasted corn tortillas, ground cumin, ground coriander, ground cloves, ground cinnamon, and a little chicken broth. Blend until smooth to make a paste.

Add the paste to the pot with the chicken and vegetables. Stir well to combine.

Pour in the remaining chicken broth to the pot, ensuring all ingredients are submerged. Bring to a simmer.

Cover the pot and let the stew simmer over low heat for about 30-40 minutes, or until the chicken is cooked through and the vegetables are tender.

Season with salt and pepper to taste.

Serve the pepián de pollo hot, garnished with chopped fresh cilantro.