Preheat the grill to medium-high heat (about 400°F).
Wash and scrub the sweet potatoes thoroughly. Pat them dry with a towel.
Cut each sweet potato into 1/2-inch thick rounds, ensuring even sizes for consistent cooking.
In a large bowl, combine the olive oil, garlic powder, paprika, salt, and black pepper. Stir well to create a marinade.
Add the sweet potato rounds to the bowl and toss them until evenly coated with the marinade.
Prepare a piece of aluminum foil large enough to hold the sweet potatoes. Place the coated sweet potatoes onto the foil, fold it over to create a sealed packet, ensuring no oil escapes.
Place the packet directly onto the grill grates. Cook for about 10-15 minutes, turning the packet halfway through for even cooking.
Check for tenderness by piercing a sweet potato round with a fork; they should be fork-tender and slightly caramelized.
Remove the foil packet from the grill using tongs, let it cool for a moment, then open carefully to avoid steam.
Serve warm, optionally topped with fresh herbs, feta cheese, or a squeeze of lime juice.