Using a mortar and pestle, smash the garlic, the broken-up dried chiles, the chopped shallot, and a good pinch of salt to a paste. Put the paste in the slow cooker with the pork ribs, 6 cups (1.4 L) water, several grindings of pepper, the fish sauce, miso paste, and tamarind. Cover and cook on low for 8 hours.
Morning or Evening
In a large skillet or sauté pan, heat 4 tablespoons (60 ml) of the oil over medium-high heat. When it shimmers, add the sliced shallot and cook, stirring with a slotted spoon, until deeply browned, 5 to 6 minutes. Remove to a paper towel to drain. Return the oil to medium-high heat, add the whole dried chiles, and cook for 30 seconds, until just darkened a shade. Remove to the paper towel to drain. Set aside at room temperature; keep the skillet handy (no need to wash it yet).
Place the skillet with any remaining oil (add a little oil, if needed) over medium-high heat. Add the greens and stir until just wilted, then cover and cook until the thickest stems are tender, about 10 minutes, stirring occasionally and adding about ½ cup (60 ml) water if they start to stick to the pan. Gently fold the greens into the soup in the cooker (the ribs will be falling-off-the-bone tender; fish out and discard the bones, if you’d like), season with more salt or fish sauce, if needed, and serve with the fried shallot and chiles on the side for topping.