Preheat oven to 425F. Spread broccolini on a baking tray and top with olive oil, vinegar, garlic, salt, and pepper; toss to coat. roast 15 to 20 minutes, or until tender.
Line 7x11-inch baking dish with parchment paper. Lay out 2 slices of prosciutto, overlapping slightly on the longest edge. Place a salmon fillet in the center; fold prosciutto over it. repeat for all the fillets and place in baking dish.
Roast 10 to 12 minutes, or until salmon is cooked through but slightly pink in the center. Serve with broccolini.