Preheat grill to medium heat.
Grill the bacon and onion slices until the bacon is very crispy and the onion slices are tender. About 4-6 minutes per side.
Lightly coat the potatoes with olive oil, salt, and freshly ground pepper. Wrap loosely in aluminum foil and place on grill for about 15 minutes, turning over once about halfway through.
Remove bacon, onions, and potatoes from the grill and let cool completely.
Dice the bacon and onions into small pieces and combine with potatoes in a large bowl.
In a separate bowl, mix together the onion powder, garlic powder, cayenne pepper, salt, and pepper.
Combine the spice mixture (or Lobel's Dry Rub) with bacon, potatoes, and onions, then stir in the mustard and mayonnaise.
Refrigerate one hour before serving.