Spread about 3/4 teaspoon mustard over each bread slice. Place 1 cheese slice on each of 4 bread slices. Divide turkey evenly over cheese. Top each serving with 2 1/2 tablespoons sauerkraut and 1 tablespoon dressing. Top each serving with 1 bread slice, mustard sides down.
Heat 1 1/2 teaspoons canola oil in a large nonstick skillet over medium-high heat. Add 2 sandwiches to pan; top with another heavy skillet. Cook 3 minutes on each side or until golden; remove sandwiches from pan, and keep warm. Repeat procedure with remaining oil and sandwiches.