Lay out a large sheet of heavy-duty aluminum foil.
Place 1 thickly sliced zucchini, 1 thickly sliced yellow squash, ½ red onion cut into chunks, 1 red bell pepper cut into chunks, and 1 green bell pepper cut into chunks in the center of the foil.
Drizzle 1 Tbsp olive oil evenly over the vegetables.
Sprinkle 1 tsp salt, 1 tsp black pepper, and 2 tsp minced garlic over the vegetables.
Toss the vegetables gently on the foil until evenly coated with the oil and seasonings.
Fold the foil tightly around the vegetables to create a sealed foil packet.
Preheat the grill to medium-high heat (approximately 400°F).
Place the foil packet on the grill and cook for 5–8 minutes.
Flip the packet once halfway through the cooking time.
Carefully open the foil packet and check that the vegetables are tender.
Remove from the grill and serve immediately.
Enjoy!
Notes
*Refrigerate any leftovers in an airtight container for up to 5 days. *You can use any type of cooking oil that you prefer in this recipe.