The secret to this vegetarian Reuben sandwich is a carrot and parsnip slaw that’s inspired by the flavors of pastrami. The spicy, sweet and smoky seasoning makes it reminiscent of the deli counter classic. When combined with homemade dressing, gooey melted cheese and griddle-toasted bread, it makes for a meatless meal that’s been known to satisfy even the staunchest Reuben purists!
Make the slaw: Combine all the ingredients in a large bowl. Mix well until evenly combined, then let sit for at least 10 minutes. (The slaw can be made up to 3 days in advance and kept in an air-tight container in the refrigerator; stir well before using).
Make the dressing: Whisk together all the ingredients in a small bowl. Set aside until ready to assemble the sandwiches. (The dressing can be made in advance and will keep covered in the fridge for up to 1 week.)
Assemble the sandwiches: Heat 1 tablespoon of the olive oil or butter in a heavy-bottomed skillet or a griddle over medium heat. Add a heaping cup of the slaw and the sauerkraut to the skillet and cook, stirring occasionally, just until heated through, 1 to 2 minutes. (You will extra slaw left over.)
Meanwhile, spread the dressing on the bread, reserving some for dipping. Once the slaw and sauerkraut are hot, divide between the bottom slices of bread. Top each with 4 overlapping slices of Swiss then close the sandwiches.
Use a paper towel to wipe the skillet clean, then add another tablespoon of butter or olive oil to the skillet and heat over medium heat until the butter melts or the oil is hot. Working with 1 at a time, place a sandwich in the center. Top with a pan lid or smaller heavy skillet to press the sandwich down. Reduce the heat to low and let cook 2 minutes then flip and cook the other side until both sides of the bread are toasted and the cheese has melted. Repeat with the second sandwich.
Cut the sandwiches in half and serve hot with additional dressing on the side, for dipping. Serve with a pickle spear and potato chips or your favorite side.