Prepare the grill for direct cooking over medium heat (350° to 450°F). Brush the cooking grates clean. Cut the onions in half lengthwise, then slice into ¼-inch-thick half-moons.
In a large bowl combine the onions, oil, thyme, and salt and toss to coat the onions evenly.
Related Grill Skills
Spread the onion mixture in an even layer on a large perforated grill pan.
Set the grill pan over direct medium heat and cook the onions, with the lid closed, until soft and golden brown, 25 to 35 minutes, stirring about every 5 minutes.
Set the grill pan over medium heat and cook the onions, with the lid closed, until soft and golden brown, 25 to 35 minutes, stirring about every 5 minutes.
Remove the grill pan from the grill and let the onions cool to room temperature. Discard any onion bits that have turned black (to avoid any unwanted bitter flavors).
In a food processor combine all of the dip ingredients except the chives. Process until blended. Add the onions and pulse to a dip consistency with some onion pieces remaining. Add all but ½ teaspoon chives and pulse once. Transfer to a bowl, sprinkle with the reserved chives, and serve with the chips.