Cut 3 pounds red potatoes into ¾-inch chunks (peel first if desired). Place the potatoes and 2 teaspoons of the kosher salt in a large pot. Add enough cold water to cover the potatoes by about 1 inch. Bring to a boil over high heat. Reduce the heat to maintain a gentle simmer, and cook until the potatoes are fork-tender, 8 to 10 minutes.

Meanwhile, cook 4 chopped thick-cut bacon slices in a medium skillet over medium heat until crisp and browned, 6 to 8 minutes. Turn off the heat. Using a slotted spoon, transfer the bacon to a paper towel-lined plate. Transfer 1 tablespoon of the bacon fat in the skillet into a large bowl; discard the remaining fat.

When the potatoes are ready, drain well in a colander. Transfer to a baking sheet and spread into a single layer. Let cool to room temperature, about 15 minutes.

Whisk ¾ cup mayonnaise, ¾ cup sour cream, 3 tablespoons ranch seasoning, 1 tablespoon prepared yellow mustard, 2 teaspoons minced chipotle peppers in adobo, ½ teaspoon black pepper, and the remaining ¾ teaspoon kosher salt into the reserved bacon fat.

Reserve 1 tablespoon thinly sliced dark green scallion parts and 1 ounce of the shredded sharp cheddar cheese (about ¼ cup) for garnish. Add the cooled potatoes, remaining thinly sliced scallions, 4 ounces shredded cheddar cheese, and 4 diced medium celery stalks to the bowl of dressing and fold to combine.

Cover and refrigerate for at least 30 minutes or up to 1 day before serving. Refrigerate the cooked bacon and reserved scallions and cheddar cheese in an airtight container. Just before serving, taste and season with more minced chipotle peppers, kosher salt, and black pepper as needed. Garnish with the reserved bacon, scallions, and cheddar.