A few tablespoons chopped roasted peanuts, for garnish
A few sprigs of parsley, for garnish
In a large skillet, heat the oil over moderately high heat. Add the onion and cook, stirring regularly, until richly browned, about 10 minutes. Add the sliced chard and potatoes, cover and cook about 3 minutes (just to wilt the chard). Uncover and cook, stirring frequently, until the chard is tender and the mixture dry, about 5 minutes longer. Taste and season with salt. Remove from the heat. (If not completing the enchiladas immediately, spread the mixture onto a baking sheet and cool completely; return to pan before continuing.)
Set up a steamer (a vegetable steamer in a large saucepan filled with 1-inch of water works well); heat to a boil. Wrap the tortillas in a heavy kitchen towel and lay them in the steamer; cover tightly. Boil 1 minute, turn off the heat and let stand without opening the steamer for about 15 minutes.
While the tortillas are standing, bring the mole to a simmer in a medium-size saucepan. Taste and season with additional salt if necessary; thin with additional water or broth to the consistency of a medium cream soup. Warm the filling over medium-low heat.
When ready to serve, make enchiladas a portion at a time: Lay 2 tortillas on a warm dinner plate, roll a portion of the filling into each one, lay the enchiladas seam-side down on the plate and ladle a portion of the mole over the top—cover the tortilla completely; be generous with the sauce. Sprinkle with peanuts and parsley leaves. Serve immediately.