Preheat oven to 350°F (175°C) and lightly grease a baking dish.
Slice slider buns in half horizontally and place the bottom halves in the dish.
Spread Thousand Island dressing over the buns.
Layer with corned beef, Swiss cheese, and sauerkraut.
Add the top halves of the buns to complete the sliders.
In a small bowl, mix melted butter, Dijon mustard, minced onion, Worcestershire sauce, and poppy seeds.
Brush the butter mixture over the tops of the sliders.
Cover with foil and bake for 20 minutes. Remove foil and bake an additional 5 minutes or until tops are golden.
Serve warm and enjoy!