Pierce the potatoes all over with a fork. Place on a microwave-safe plate and microwave until tender, about 15 minutes. Let cool 10 minutes, then gently flatten the potatoes with your hand until about 3/4 inch thick. Slice each in half horizontally to make 2 slices of "bread." Season the insides with salt and pepper.
Meanwhile, bring a medium saucepan of salted water to a boil. Add the broccoli and cook until bright green and tender, about 2 minutes. Drain and run under cold water to stop the cooking, then transfer to a paper towel¿lined plate to dry.
Cook the bacon in a large nonstick skillet over medium-high heat, turning, until crisp, about 7 minutes. Drain on a paper towel¿lined plate; break each slice in half. Make the chive sour cream: Blend the sour cream, chives, vinegar and 1/4 teaspoon salt in a food processor until pale green and smooth, about 1 minute. Transfer to a small bowl.
Build the sandwiches: Layer the muenster, bacon, broccoli and jarlsberg on 4 potato halves, then top with the remaining potato halves. Heat the vegetable oil in a large nonstick skillet over medium-high heat. Add the potato sandwiches and place a heavy skillet on top. Cook until browned and crisp and the cheese is melted, 3 to 4 minutes per side. Season with salt and pepper. Cut in half and serve with the chive sour cream and hot sauce.
Photograph by Jeff Harris