Preheat oven to 400 degrees. Combine the orange juice, vinegar, 3 tablespoons of olive oil, chopped herbs and chopped onion in a small bowl. Coat a 9 x 13 dish with the 2 tablespoons of olive oil and heat dish in preheated oven until hot. Add the salmon fillets in a single layer. Pour orange juice mixture over the fillets. Bake for 13 minutes. Baste with sauce once or twice while baking. Broil for 5 minutes or until lightly browned and crusty. Remove, garnish with parsley and orange slices.