Preheat the grill to 400°F or medium-high heat. Clean and oil the cooking grate, then close the lid.

In a small microwave-safe bowl, combine butter, garlic, salt, and pepper. Microwave for 1 minute to melt the butter. Stir in parsley and set aside.

Quarter the bell peppers and remove seeds and ribs.

Slice the root end off of the onion and peel the skin off of the exterior. Slice the onion into 1/2-in slices, keeping the rings together, to make 4 slices.

Place sausages on the grill alongside peppers, onion slices, and corn on the cob.

Grill the onion slices and peppers for about 10 minutes, about 4–5 minutes per side.

Grill the corn for about 10–15 minutes, turning every 3–5 minutes. Remove vegetables to a serving dish and brush with garlic butter.

Cook the sausages for about 13–15 minutes, turning frequently. Pork sausage is fully cooked when the internal temperature reaches 160°F.

Remove the sausages, brush with garlic butter, and let rest for 3 minutes before serving.