1. Heat oil in a large high-sided skillet over medium heat. Cook onions until soft, about 6 minutes. Add garlic, and cook for 1 minute. Stir in chard, beans, and stock. Cook until greens are wilted and beans are warmed through, about 4 minutes. Season with 3/4 teaspoon salt and some pepper.

2. Using tongs, hold each tortilla directly over a gas flame, turning, until heated through, about 5 seconds. (Alternatively, wrap tortillas in foil, and warm in a 350-degree oven.) Spoon filling onto tortillas. Top with cheese and cilantro.