1/2 pound sliced deli roast beef
8 slices ciabatta bread (1/2 inch thick)
1 cup fresh arugula
1 cup baby spinach
4 teaspoons olive oil
1 tablespoon lemon juice
1 tablespoon white wine vinegar
1-1/2 teaspoons prepared horseradish
Place roast beef on ciabatta slices or sturdy bread of your choice.
In a large bowl, combine arugula and romaine. In a small bowl, whisk remaining ingredients until blended. Drizzle over greens; toss to coat. Arrange over beef; serve immediately.