Preheat the oven to 400°F.
In a small bowl, whisk together the honey, Dijon mustard, olive oil, garlic powder, salt, and pepper.
Place the salmon fillets on a baking sheet lined with parchment paper. Brush the honey mustard glaze over the salmon fillets.
In a separate bowl, toss the sliced bell peppers, zucchini, yellow squash, and red onion with balsamic vinegar, olive oil, salt, and pepper.
Arrange the vegetables around the salmon fillets on the baking sheet.
Bake for 15-20 minutes, or until the salmon is cooked through and the vegetables are tender.
Serve the salmon and vegetables hot, garnished with fresh herbs if desired.