Preheat oven. Preheat the oven to high broil and line a large rimmed baking sheet with aluminum foil. If your pan feels crowded or you want extra vegetables, prepare a second sheet pan as well.

Prepare marinade. In a medium bowl, whisk together the lime juice, orange zest and juice, olive oil, soy sauce, sweet chili sauce, and water. Add the garlic, parsley, cilantro, salt, cumin, and red chili flakes (optional), then whisk again until fully combined.

Arrange on the sheet pan. Arrange the salmon fillets, bell peppers, and onion on the prepared baking sheet, placing the salmon skin-side down if using skin-on fillets.

Coat with sauce. Spoon about half of the chili lime sauce over the salmon and vegetables. Gently toss the vegetables to coat, and brush or spoon some of the sauce over the tops of the salmon fillets.

Broil. Broil for 10 to 12 minutes, rotating the pan once halfway through cooking, until the vegetables are tender and lightly charred and the salmon flakes easily with a fork. Check that the salmon has reached an internal temperature of 145°F at the thickest part, then remove it from the oven.

Garnish and serve. Serve immediately with the remaining sauce spooned over the top. Garnish with extra cilantro, lime wedges, or additional sweet chili sauce if desired.