Pour almonds in a 12-inch nonstick frying pan over medium heat. Shake or stir often until nuts are golden brown, 7 to 8 minutes. Pour from pan and set aside. Wipe frying pan clean.
Thinly slice onions and add them to frying pan along with 3 tablespoons teriyaki sauce and the olive oil. Stir often over medium heat until onions are very soft, 15 to 20 minutes.
Meanwhile, rinse salmon and pat dry. Place fillets, skin side down, on an oiled rack of a broiler pan. Brush about half the remaining teriyaki sauce over salmon. Broil salmon 4 to 6-inches from heat for 4 minutes. Brush with remaining teriyaki sauce, then continue broiling until salmon is just barely opaque in thickest part 2 to 4 more minutes.
Transfer salmon to a serving platter. Top each fillet with equal portions of onions and sprinkle with toasted almonds. Garnish with lemon wedges.