Preheat oven to 400°F.
Combine diced sweet potatoes and 1/2 tablespoon olive oil in a medium bowl and toss to coat.
Transfer sweet potatoes to a sheet pan and season with salt and pepper.
Roast for 15 minutes, tossing once halfway through.
While the sweet potatoes are roasting, make the teriyaki sauce by combining the soy sauce, rice vinegar, sesame oil, garlic, ginger and brown sugar in a medium saucepan over medium high heat.
Whisk together the cornstarch and water.
Bring the sauce to a boil, then whisk in the cornstarch slurry. Continue whisking a few more seconds until the mixture thickens.
Remove the pan from the heat, stir in the sesame seeds, and set aside to cool.
When the potatoes are done roasting, remove the sheet pan from the oven and push the potatoes out to the edges.
Place the salmon fillets in the center and brush with 1/2 tablespoon of the olive oil. Season lightly with salt and pepper.
Combine the broccoli, shallots, and remaining tablespoon of olive oil in the medium bowl used for the sweet potatoes. Season with salt and pepper, then toss well to combine.
Spread the broccoli mixture around the salmon.
Reserve 1/4 cup of the teriyaki sauce, then drizzle the remaining sauce over the salmon and vegetables.
Place the sheet pan back in the oven and roast for an additional 15 minutes, or until the salmon is slightly translucent, flakes easily with a fork, and the vegetables are fork-tender.
Serve right from the sheet pan with an extra drizzle of the sauce or alongside rice or noodles.