Roast Beef with Horseradish Mayo, Crispy Onions, and Tomato

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Flour, TooI have a hard time with change. It makes me all prickly inside, and I resist it completely. Now, of course, this isn’t entirely true, because I’m always up for improving how we do things, and I’ve learned that pushing myself outside my comfort zone often leads to good results. But when it comes to Flour sandwiches, I admit that I have a harder time with change than usual. Chef Aniceto teases me about how long and hard he worked to get me to even consider making changes on the sandwich menu. I think he’s right in saying that I eventually did it to appease him more than anything else. This roast beef was one of the happy results of his persistence. Customers complained for a few weeks about the change (we removed another sandwich to make room for this one), but now it is a wildly popular menu staple. Like with the lamb top round in the roasted lamb sandwich, you’ll have a little roast beef left over after making four sandwiches. You can roast a smaller cut, of course, but be careful because it will roast more quickly and can easily overcook.

  • Yield: 4 Sandwiches


  • 2 lb (680 to 910 g) beef roast, top or bottom round
  • 4 tsp kosher salt
  • 1 tsp freshly ground black pepper
Crispy onions
  • Vegetable oil for deep-frying
  • 2 large onions
  • 2 cups (270 g) all-purpose flour
  • ½ tsp kosher salt
Horseradish mayonnaise
  • ¼ cup (60 ml) prepared horseradish, drained
  • 1 tbsp crème fraîche
  • ¼ cup (60 ml) good-quality mayonnaise
  • 1½ tsp Dijon mustard
  • 1½ tsp whole-grain mustard
  • 8 slices Flour Focaccia or other good-quality white or wheat bread
  • 4 cups (85 g) loosely packed mesclun greens or other mild lettuce
  • 2 vine-ripened tomatoes, thinly sliced, or 1 batch Roasted Tomatoes
  • ¼ tsp kosher salt, if using fresh tomatoes
How to Make It
  1. The night before, rub the beef all over with the salt and pepper, cover with plastic wrap or place in a container with a tight-fitting lid, and let rest overnight in the fridge.
  2. The next day, take the beef out of the fridge and let rest for about 1 hour at room temperature.
  3. About 20 minutes before you are ready to roast the beef, preheat the oven to 300°F/150°C, and place a rack in the center of the oven.
  4. Put the roasting rack on one of the baking sheets and put the roast on the rack. Roast the beef for 50 to 60 minutes for a 1½-lb/680-g roast or 65 to 75 minutes for a 2-lb/910-g roast, or until the meat thermometer inserted into the thickest part of the roast registers 130°F/54°C. Start checking after 45 minutes. Once the temperature hits 100°F/38°C, the cooking goes quickly, so check every 5 minutes or so. When the temperature reaches 130°F/54°C, remove the roast from the oven and let cool. Let the roast rest in the fridge for at least 3 hours or up to overnight.
  5. Meanwhile, prepare the onions
  6. Line the second baking sheet with paper towels and set aside. Pour the vegetable oil to a depth of about 2 in/5 cm into a large saucepan and heat over medium-high heat to 350°F/180°C on the deepfry thermometer. While the oil is heating, slice the onions as thinly as possible. Scoop the flour into a large bowl. Add the onions and toss until thoroughly coated.
  7. When the oil is ready, remove about half of the onions from the flour bowl, shake them to remove the excess flour, and carefully drop them into the hot oil. As soon as you immerse the onions in the oil, the temperature of the oil will drop, so turn the heat to high to bring the oil back to 350°F/180°C. Cook the onions, stirring constantly with a slotted spoon to avoid over browning, for 5 to 7 minutes, or until golden brown. Using the slotted spoon, transfer the onions to the prepared baking sheet and sprinkle with ¼ tsp of the salt. When the oil has returned to 350°F/180°C, cook the remaining onions the same way, then transfer them to the baking sheet and sprinkle with the remaining ¼ tsp salt. The onions can be cooked up to 2 days in advance and stored in an airtight container at room temperature.
  8. To make the horseradish mayonnaise
  9. In a small bowl, stir together the horseradish, crème fraîche, mayonnaise, Dijon mustard, and wholegrain mustard until well combined. The mayonnaise can be stored in an airtight container in the fridge for up to 2 weeks.
  10. Remove the well-chilled roast from the refrigerator and slice it against the grain as thinly as possible. Set the slices aside.
  11. Lay the bread slices out on a clean, dry counter and spread them evenly with the horseradish mayo, using about 1 tbsp for each slice. Top four of the slices with the greens, dividing them evenly. Top the greens with the tomatoes; if using fresh tomatoes, sprinkle evenly with the salt. Top each sandwich with 5 to 6 oz/140 to 170 g of the sliced beef, and top the beef with the onions, dividing them evenly. Close each sandwich with a second focaccia slice, mayonnaise-side down, cut in half, and serve.

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