Prep Time: 40 minutes
Preheat the oven to 400 degrees. In a small mixing bowl, whisk together 4 Tbsp. olive oil along with the horseradish, mustard, lemon juice, garlic and Worcestershire sauce until completely blended and emulsified. Season with a pinch of salt and pepper and place in the refrigerator. Meanwhile, in a large mixing bowl, toss together the bread cubes along with 1 Tbsp. olive oil and a pinch of salt and pepper until combined. Pour on a baking sheet in a single layer and place in the oven for 15 minutes, turning once. Remove from the oven and set aside.
Season the steak generously with salt and pepper. Heat the remaining oil in a large sauté pan over a high flame until hot. Place the steak in the pan and cook for 4 minutes on each side for medium rare or 6 minutes for medium. Remove to a cutting board and rest the steak for as long as you cooked it.In a large mixing bowl, toss together the kohlrabi and romaine along with the caesar dressing and a pinch of salt. Slice the steak thinly on the bias, removing any fat or gristle. Divide the salad between 2 plates and top evenly with the steak and croutons.