Spread the tomatillos on a roasting pan along with ½ of the onion, 6 cloves garlic, and the jalapeños. Toss with 2 tablespoons of the oil and season with salt and pepper, to taste. Roast until tender, about 35 minutes.
Remove from the oven and carefully transfer the vegetables to a blender. Pureé until smooth. Add the lime juice, chopped cilantro, and 2 tablespoons of the honey and pulse to blend. Season with salt and pepper, to taste, and transfer to a bowl. Rinse out the blender.
In a medium-sized saucepan, heat the remaining oil. Chop the remaining garlic. Add the remaining onion, garlic, chipotle, and cumin, and cook over moderate heat, stirring occasionally, until the onion is softened, about 5 minutes.
Add the beans with their liquid and the water and cook over low heat for 15 minutes. Transfer the bean mixture to the blender and purée until smooth. Season with salt, to taste.
Light a grill or preheat a grill pan over moderately high heat. In a small bowl, combine the remaining honey with the ancho chili powder and mustard and season with salt, to taste. Brush the salmon with oil and season with salt and pepper, to taste.
Grill the fish skin side down until very crisp, about 3 minutes. Cook the fish on the remaining 3 sides until just lightly charred, 3 more minutes. Brush the salmon with the chile-honey glaze and grill skin side up until lightly caramelized, 2 minutes.
Spoon the tomatillo salsa on plates and top with the grilled salmon. Garnish with the cilantro sprigs and serve with sour cream and the black bean sauce.