In same large bowl, mix brown sugar, 2 tablespoons soy sauce, the butter, vinegar and 1/4 teaspoon salt. Transfer 2 tablespoons of the mixture to medium bowl. Add salmon to mixture in medium bowl; turn to coat. Add broccoli to large bowl, and toss to coat. Add salmon, skin side down, to pan with potatoes; add broccoli. Pour any remaining mixture from both bowls over salmon and broccoli. Roast 12 to 15 minutes or until salmon is cooked through and flakes easily with a fork, and potatoes are fork-tender. Top with green onions.