Preheat your oven to 400°F and line a large sheet pan with parchment paper for easy cleanup.
In a medium bowl, toss the chickpeas, broccoli florets, and sliced bell peppers with the olive oil, sea salt, and black pepper until evenly coated.
Spread the vegetables in a single layer on the prepared baking sheet, leaving space in the center for the salmon fillet.
In a small ramekin, whisk together the Dijon mustard, dried parsley, dried dill, and garlic powder to create a thick herb paste.
Pat the salmon fillet dry with a paper towel and place it in the center of the baking sheet, then spread the herb paste generously over the top.
Roast for 12 to 15 minutes, or until the salmon is opaque and flakes easily with a fork and the vegetables are tender.
Remove from the oven and drizzle the entire tray with fresh lemon juice before serving warm.