How to Make It
In a large pot, cover the potatoes with cold salted water and bring to a boil over moderately high heat. Cook until the potatoes are tender, about 35 minutes. Drain the potatoes and, when they are cool enough to handle, slice them in half.
Meanwhile, in a medium skillet, cook the bacon slices over moderate heat until crisp, about 6 minutes. Drain on paper towels and coarsely crumble.
In a large bowl, mix the mayonnaise with the barbecue sauce, mustard oil and sherry vinegar. Fold the potatoes into the dressing while they are still warm. Let the potato salad stand, stirring a few times, until the potatoes have cooled and absorbed most of the dressing, about 20 minutes.
Add the celery, red onion, parsley and tarragon to the potatoes and season with salt and pepper. Let stand for an additional 20 minutes, stirring a few times. Garnish with the bacon and sprouts, then serve.