In a bowl, cover the anchos and chipotles with the boiling water.
Let soak for 30 minutes, until softened.
Drain, reserving the liquid. Discard the stems, cores and seeds; coarsely chop the chiles.
Preheat the broiler or light a gas flame. Char the peppers for 10 minutes, turning occasionally, until charred all over.
Transfer to a medium bowl, cover with plastic and let steam for 5 minutes. Peel the peppers and discard the skin, stems and seeds, then coarsely chop.
In a small dry skillet, toast the cloves, cumin and cinnamon stick over moderately low heat until darkened and fragrant, 1 1/2 minutes.
Let cool. Grind to a powder in a spice grinder.
Transfer to a plate.
Add the sunflower seeds to the skillet and toast, shaking the pan a few times, about 3 minutes.
Let cool.
Transfer the seeds to the grinder; finely grind.
Heat the oil in a medium skillet.
Add the garlic and cook over low heat until golden, about 3 minutes.
Add the tomato paste and cook, stirring, until glossy, about 2 minutes.
Remove from the heat and stir in the chocolate until melted.
In a blender, combine the chiles and their soaking liquid with the bell peppers, the ground spices, the ground sunflower seeds and the garlic mixture and blend until smooth. Scrape the mole into a large bowl and season with salt.
Transfer the sauce to jars and refrigerate.
Make Ahead: The sauce can be refrigerated for 3 weeks.