Rinse the beans and put them in the slow cooker with the corn, epazote, onion, and
Coarsely chop the chard, including the stems, and mince the garlic. If doing this in the morning, cover and refrigerate.
Turn the cooker to high and season the stew with salt and pepper.
In a large skillet or sauté pan, heat the oil over medium-high heat. When it shimmers, add the chard and garlic and a pinch of salt and cook, tossing with tongs, until just tender, 5 to 7 minutes, adding a splash of water, if needed, to keep the leaves from sticking. Gently fold into the stew. Serve.