Combine the larger portion of vinegar, water, allspice, salt, peppercorns, thyme, and paprika in a large saucepan and bring to a simmer over medium heat. Add the tempeh pieces, cover, and reduce the heat to medium-low. Simmer until the liquid is mostly absorbed, 10 to 15 minutes, turning the tempeh halfway through to ensure even seasoning.

Transfer the tempeh to a plate and let it cool for 10 minutes. This allows the proteins to set so the pieces don't fall apart during frying.

Cook the sauerkraut, remaining two tablespoons of vinegar, and sugar in a 12-inch nonstick skillet over medium-high heat. Stir occasionally until the liquid has completely evaporated, about 3 minutes, then transfer to a bowl and wipe the skillet clean.

Heat half the oil in the skillet over medium heat until it shimmers. Add half of the tempeh and cook until the first side is deeply golden brown, 2 to 4 minutes. Flip the pieces, reduce the heat to medium-low, and continue cooking until the second side is browned. Transfer to a plate, wipe the skillet, and repeat with the remaining oil and tempeh.

Whisk the mayonnaise, chopped pickles, brine, and cocktail sauce together in a small bowl. Brush the melted butter over one side of each bread slice. Flip the bread and spread the mayonnaise mixture evenly over the unbuttered side.

Assemble the sandwiches by layering a slice of Swiss cheese, the fried tempeh, the prepared sauerkraut, and a second slice of Swiss cheese between the bread slices. Press gently to help the layers adhere.

Heat the skillet over medium-low heat for 2 minutes. Place two sandwiches in the pan and cook until the bottom is golden brown, about 2 minutes. Flip, cover the skillet to trap heat, and cook until the second side is golden and the cheese is fully melted. Repeat with the remaining sandwiches.

Serve immediately while the bread is still hot and crisp and the cheese is pulling.