In a large baking dish, whisk the oil, vinegar, thyme, salt, and pepper. Add the onions and gently turn the slices over in the oil mixture, being careful to keep them from falling apart. Set aside to marinate at room temperature for 2 to 4 hours.
Related Grill Skills
Slicing an Onion
Prepare the grill for direct cooking over medium heat (180° to 230°C).
Prepare the grill for cooking over medium heat (200°C).
Brush the cooking grates clean. Grill the onions and bratwurst over direct medium heat, with the lid closed, until the onions are tender and the bratwurst are browned, 10 to 12 minutes, turning occasionally. During the last 30 seconds of grilling time, place the rolls, cut side down, on the grill to toast. Remove from the grill. Separate the onion slices into rings. Place a bratwurst in each roll and spoon the onions on top. Serve mustard on the side.
Brush the cooking grates clean. Grill the onions and bratwurst over medium heat, with the lid closed, until the onions are tender and the bratwurst are browned, 10 to 12 minutes, turning occasionally. During the last 30 seconds of grilling time, place the rolls, cut side down, on the grill to toast. Remove from the grill. Separate the onion slices into rings. Place a bratwurst in each roll and spoon the onions on top. Serve mustard on the side.
