Preheat oven to 475 degrees F. Slice ends off of Brussels sprouts and remove outermost leaves. Slice thin with a knife or use a food processor fitted with a slicing blade. Toss sprouts and diced apples with olive oil and salt. Line a sheet pan with Reynolds Wrap® Heavy Duty Foil and roast sprouts and apples for 20 minutes, stirring after 10 minutes.
In a skillet over medium heat, cook pancetta until crisp, about 5 minutes. Remove pancetta and leave 3 tablespoons of the grease. Add the onion and garlic and cook about 2 minutes. Add the radicchio, separating the quarters and stir until the leaves wilt. Add Brussels sprouts and pancetta, and toss to combine. Add vinegar and honey.