How to Make It
Peel the onions. Using a sharp paring knife and starting at the top (opposite the stem end), cut an inverted cone-shaped cavity, about 2 1/2 inches across and 1-inch deep (the core will come out in a cone-shaped plug). Finely chop the pieces you remove from each onion. Set the onions, stem side down, on the foil rings.
Melt 1 tablespoon butter in a skillet. Add the bacon and chopped onion and cook over medium heat until lightly browned, 3 to 5 minutes. Add the pecans after 2 minutes. Drain the bacon mixture in a strainer over a bowl, reserving the fat. Place a spoonful of bacon-mixture in the cavity of each onion. Spoon in some barbecue sauce and place a pat of butter (cut from the remaining butter) on top. Grind some fresh pepper on top of each onion. Brush the sides of the onions with bacon fat. The recipe can be prepared several hours ahead to this stage.
Set up your grill for indirect grilling and preheat to medium. If using a gas grill, place the wood chips in the smoker box or a smoker pouch and run the grill on high until you see smoke, then reduce the heat to medium. If using a charcoal grill, toss the wood chips on the coals.
Place the onions on the grate away from the fire. Indirect grill until onions are golden brown and tender, 40 to 60 minutes. To test for doneness, pinch the sides of the onion--they should be squeezably soft. If the filling starts to brown too much before the onions are fully cooked, tent with foil. Transfer the onions to a platter or plates and get ready to experience the lowly onion elevated to the level of art.