Preheat oven to 450°F. Leaving the skins on, cut the potatoes into quarters and place them onto a large sheet pan.

Drizzle the potatoes with oil and minced rosemary, then season with garlic salt, kosher salt, and freshly ground black pepper. Using your hands, toss the potatoes until well coated.

Roast the potatoes undisturbed for 30 minutes, or until the bottoms are golden brown. Flip the potatoes and continue cooking until fork tender, another 10-15 minutes. The larger the potato chunks the longer they will take to cook.

While the potatoes are cooking, fry the bacon until crisp, drain on paper towels, and cut into bite-size pieces.

In a small bowl, mix the mayonnaise with the red wine vinegar, Dijon mustard, and whole-grain mustard. Add a generous pinch of kosher salt and a few grinds of pepper. Mix well.

Once the potatoes are done, remove from the oven and set then set them aside to cool for 5-10 minutes.

Transfer the potatoes to a large bowl with ¾ of the dressing and toss to coat. Add the chopped bacon, red onion, chopped egg, and chives and toss again. Add more dressing as desired. Taste for seasoning and adjust as needed. Top with more chopped chives and rosemary if you like. Serve warm or at room temperature.