Warm Roast Beef and Onion Sandwiches with Garlic Horseradish Sauce - Ontario Beef
clock icon cutlery icon flag icon folder icon instagram icon pinterest icon facebook icon print icon squares icon heart icon heart solid icon

Warm Roast Beef and Onion Sandwiches with Garlic Horseradish Sauce

  • Author: jennkyle
  • Prep Time: 30 minutes
  • Cook Time: 2 hours 30 minutes
  • Total Time: 3 hours
  • Yield: 6 servings 1x


Have you ever looked at a cost-effective Eye of Round beef roast and thought, how would I cook that? Well, Chef Paul Lillakas shows us that it happens to be ideal for making delicious homemade roast beef, perfect for layering into an impressive deli-style sandwich!




  • 2 large sweet onions, thickly sliced
  • 1.5 kg Ontario Eye of Round beef roast
  • 2 tbsp olive oil
  • 1 tbsp sea salt
  • 2 tsp black pepper


  • 1 cup mayonnaise
  • 1 cup sour cream
  • 2 tbsp hot prepared horseradish
  • 2 cloves garlic, minced or grated
  • 1 tsp black pepper
  • 1/2 tsp sea salt

For the Sandwiches:

  • 6 cups baby arugula
  • 2 large ciabatta baguettes, each cut into thirds and halved lengthwise (optional: wrapped in foil and baked for 5 minutes to warm


  1. Preheat oven to 250F. Line baking sheet with parchment paper.
  2. Place onions onto the prepared pan. Holding roast over onions, drizzle with oil and season with salt and pepper letting excess fall onto the onions. Toss to coat. Place roast into the centre of the pan.
  3. Roast until instant-read thermometer inserted into thickest part of roast reads 125F, about 2-2 1/2 hours. (Tip: test at multiple points of roast to be sure) Remove roast from oven. Increase temperature to 550F (convection if possible).
  4. Sauce: In bowl, combine mayonnaise, sour cream, horseradish, garlic, pepper and salt. Cover and refrigerate for minimum 1 hour or overnight.
  5. Place roast in oven until well browned. Remove; cover with foil and rest for at least 30 minutes. Meanwhile, stir onions and return to oven. Continue to cook until browned, about 6-8 minutes more. Slice beef as thinly as possible. Tip: this roast can be made up to 3 days ahead of time and sliced cold with greater ease.
  6. Assembly: Slather bread with sauce; layer on sliced beef, roasted onions and arugula. Sandwich with top bun. Serve immediately or wrap in parchment and refrigerate for lunches.