Preheat the oven to 400°F.
Place the farro, 2 cups of water and a pinch of salt in a medium pot over medium heat. Bring to a boil, reduce the heat to a simmer and cook until the grains are tender, about 20 minutes.
On a baking sheet, toss the tomatillos and onion with 1 tablespoon canola oil, salt and pepper and roast for 12-15 minutes, until golden. Transfer to a blender and purée until smooth. Season to taste.
Place the black beans in a large heatproof bowl. In a medium saucepan, heat the oil, garlic, and cumin until the garlic starts to turn golden. Pour the spiced oil over the black beans and toss to coat. Add the farro, goat cheese, queso fresco, puréed chipotles in adobo, salt and pepper, and toss to coat.
Lay the tortillas on a work surface and divide the farro filling between them. Roll to close and place the filled enchiladas seam side down in a large baking dish. Pour the tomatillo salsa on top, sprinkle with the shredded Oaxaca cheese, and bake for 20 minutes, until the cheese is melted and bubbly.
In a large bowl, whisk together the cumin, vinegar, salt and pepper. Fold in the cabbage, jalapeños, and red onion.
Serve the enchiladas hot with pickled cabbage slaw.