01 - Set your grill to medium-high heat, targeting approximately 400°F. Allow the grates to fully heat before placing the foil packets.
02 - In a large mixing bowl, combine the quartered baby potatoes and sliced red onion. Add the chopped parsley, rosemary, thyme, minced garlic, kosher salt, black pepper, and olive oil. Toss thoroughly until all pieces are evenly coated with the herb and oil mixture.
03 - Tear two large sheets of heavy-duty aluminum foil. Divide the seasoned potato mixture evenly between the two sheets, piling it in the center of each. If using, sprinkle with grated Parmesan cheese and smoked paprika at this stage.
04 - Fold the foil over each portion of potatoes and crimp all edges tightly shut to form well-sealed packets that will trap steam during cooking.
05 - Place the sealed foil packets onto the preheated grill. Cook for 20 to 25 minutes, flipping once halfway through, until the potatoes are fork-tender and lightly golden on the edges.
06 - Carefully open each foil packet, watching for escaping steam. Transfer the potatoes to a serving dish and garnish with additional fresh herbs if desired. Serve immediately while hot.