- 1 1/2 pounds broccoli
- 2 tablespoons white-wine vinegar
- 1/4 cup drained bottled horseradish
- 2 teaspoons Dijon mustard
- 3/4 teaspoon salt
- 1/8 teaspoon fresh-ground black pepper
- 1/2 cup olive or other oil
- 3 tablespoons sour cream
- 3/4 pound thick-sliced (1/8 inch) roast beef, cut crosswise into 1/2-inch strips
- 2 1/2 cups halved cherry tomatoes
- 6 scallions including green tops, cut diagonally into thin slices
- Separate the broccoli tops into small florets. Peel the broccoli stems and cut them in half lengthwise and then into 1/4-inch slices. In a large saucepan, steam or boil the broccoli until tender, 4 to 5 minutes. Drain and let cool.
- In a large glass or stainless-steel bowl, whisk together the vinegar, horseradish, mustard, salt, and pepper. Add the oil slowly, whisking. Whisk in the sour cream. Add the broccoli, beef, tomatoes, and scallions and toss to coat.