Preheat your grill to medium-high heat (around 400°F – 450°F) or your oven to 400°F. Grab 4 large pieces of aluminum foil, about 12x16 inches each, and give them a quick spray with nonstick cooking spray.
Bring a large pot of water to a boil. Carefully add the halved or quartered red baby potatoes and corn pieces to the boiling water. Let them cook for about 7 minutes until they are slightly tender but still firm (al dente). Drain them well and set aside.
In a big bowl, whisk together the melted butter, olive oil, fresh lemon juice, salt, pepper, and your chosen Cajun seasoning (or other preferred seasoning).
Add the parboiled potatoes and corn, sliced sausage, fresh shrimp, and chopped parsley to the bowl with the sauce. Toss gently until all the ingredients are beautifully coated.
Divide the seasoned mixture evenly among the four prepared foil sheets, placing it right in the center of each. Make sure each packet gets a good mix of shrimp, sausage, potatoes, and corn.
Seal each aluminum foil packet tightly by folding up all the sides to create a secure pouch.For the Grill: Place the packets directly on the preheated grill. Cook for 4 to 6 minutes on each side, until the shrimp turn pink and the vegetables are tender.For the Oven: Arrange the foil packets on a baking sheet. Bake for 15 to 20 minutes in the preheated oven. Once cooked, let the packets rest for about 5 minutes. Carefully open them, plate your delicious meal, and garnish with a sprinkle of fresh parsley and a lemon wedge for extra zest!