Preheat the oven to 425ºF. Season the salmon filets with salt and pepper and place skin side up on a plate. Refrigerate uncovered while you make the salsa.
Place the tomatillos, onion, Poblano pepper and garlic on a baking sheet. Squeeze the lime halves over the vegetables; season with salt. Drizzle the ¼ cup olive oil over and toss well, until all of the ingredients are coated. Spread the vegetables out evenly and roast, tossing occasionally, until the tomatillos have softened, about 15 minutes. Carefully remove the baking sheet and move a rack to about 6 inches below the broiler. Turn on the broiler.
Scatter the beans on the baking sheet with the vegetables. Nestle the salmon, skin side up, in between the beans and vegetables on the baking sheet, leaving at least 1 inch between each filet. Drizzle the skins with olive oil. Broil until the skins are blistery and crisp and the salmon is medium rare to medium, about 10 minutes (a meat thermometer stuck into the thickest part should read 120ºF).
Divide the salmon among 4 plates and serve with the tomatillo salsa and beans. Offer sour cream, cilantro and lime wedges on the side.