Make the filling. On an ungreased griddle or small (10-inch) heavy skillet set over medium heat, roast the garlic, turning frequently, until blackened in spots and soft to the touch, about 15 minutes. Cool, peel off the papery skins and finely chop. Set a 4-quart pot of water to boil and briefly blanch the kale. Transfer to a colander to drain, then roughly chop.
Heat a grill or grill pan over medium heat and place the cut half of the onion on the grill grates (or grill pan) and cook until softened, about 15 minutes
Roast the chiles directly over a gas flame (or 4 inches below a very hot broiler) until blackened on all sides, about 5 minutes for open flame, about 10 minutes for broiler. Cover with a kitchen towel and let stand 5 minutes. Peel the skins, pull out the stem and seed pod, then rinse briefly to remove bits of seeds and skin. Chop the chiles into 1/4-inch pieces.
In a medium-size bowl, mix together the garlic, kale, ricotta and the chopped chiles. Taste and season with salt (usually about ½ teaspoon) and pepper (about ¼ teaspoon). Scoop into a serving bowl.
Finishing the dish. Serve the warm tortillas and ricotta mixture for your guests to help themselves to. Set out the radishes, cilantro and salsa for everyone to add to their liking.