Preheat your grill to medium-high heat and line a baking sheet for the vegetables.
In a small bowl, whisk together the juice of 1/2 lemon, minced garlic, olive oil, salt, and pepper to create the marinade.
Place the salmon fillet in a shallow dish and pour the marinade over it, ensuring it is evenly coated. Let it sit for 10-15 minutes.
While the salmon marinates, chop the zucchini, red bell pepper, and red onion into bite-sized pieces. Toss the vegetables with a drizzle of olive oil, salt, and pepper.
Arrange the vegetables on the prepared baking sheet and roast in a preheated oven at 400°F for about 15-20 minutes until tender and slightly charred.
Grill the salmon on the preheated grill for about 4-5 minutes per side or until it reaches your desired level of doneness.
Plate the grilled salmon alongside the roasted vegetables and serve immediately, garnished with a lemon wedge if desired.