It's dinner time!

Ingredients

• 1 ½ pounds broccoli - cut into florets, stems peeled and sliced 1/4 inch thick
• 2 tablespoons white wine vinegar
• 2 teaspoons Dijon mustard
• ½ teaspoon prepared horseradish, or to taste
• ¾ teaspoon salt
• ⅛ teaspoon ground black pepper
• ½ cup olive oil
• 3 tablespoons sour cream
• ¾ pound thick sliced deli roast beef, cut into 1/2-inch pieces
• 2 ½ cups cherry tomatoes, halved
• 6 green onions cut diagonally into thin slices