For the Russian-style dressing: In bowl, mix dressing of sour cream, relish, ketchup, chives, salt, and pepper.
For the BBQ Brisket Sauce: Combine the ketchup Worcestershire sauce, vinegar, brown sugar, bay leaves, garlic, paprika, ground cloves, and black pepper in a small pot and reduce over low heat, 30 minutes. Cool and store for make-ahead meal with cooked, sliced brisket.
Warm the sauerkraut in a small pan.
Heat a sandwich press or a large griddle pan over medium heat.
Place a slice of Swiss cheese, folded to fit the bread, on 4 slices of bread, lightly buttered on one side and the buttered side facing out. Divide the meat among the sandwiches. Top the meat with some sauerkraut and another slice of cheese. Slather some dressing on the remaining sliced bread, lightly butter the side facing out.
Press the sammies on a sandwich press until the cheese melts or griddle the sandwiches until deeply golden on each side. Serve the sandwiches with halved deli pickles and salted radishes.
Store in a container and chill for a tangy Russian dressing for Reubens later in the week. The night you want to make sandwiches, reheat the brisket in the homemade barbecue sauce in a covered skillet, add a splash of stock or water to get things going if the sauce is too tight, then uncover and keep warm over low heat.