Preheat the oven to 425ºF. Line a rimmed baking sheet with parchment paper for easy cleanup.
Add the green beans to the baking sheet. Drizzle with olive oil and sprinkle with salt, pepper, and garlic powder. Toss to coat, then arrange the green beans in a single layer. Transfer to the oven and cook for 10 minutes.
While the green beans cook, add the salmon marinade ingredients to a small bowl and combine: balsamic, olive oil, dried herb blend, garlic, salt, pepper, and red pepper flakes.
Pat the salmon fillets dry and set aside.
Remove the sheet pan from the oven after 10 minutes and scoot the green beans to the sides of the pan. Add the salmon fillets to the center, and spoon the salmon marinade over top.
Return to the oven and bake for 5 minutes. Turn the broiler on, and broil for 5 more minutes to finish cooking the salmon and add some color.