Roast Beef and Watercress Sandwiches (WW recipe)

This recipe is from the Weight Watchers in 20 Minutes cook book. I make 1/4 of the recipe each day so that I can have a nice fresh sandwich every day. It does occur to me now that you could make the dressing all at once and keep it in the fridge.
The horseradish, spicy mustard and peppery watercress make this feel like a Prime Rib sandwich. So yummy! My bread is slightly higher in points but it's a larger farm style loaf so cutting one slice in half works well for me.
According to the book one sandwich is 4 points. But IMO you may need to adjust that for the bread and sour cream that you are using.

Roast Beef and Watercress Sandwiches
Serves 4

3Tablespoons light sour cream
1 Tablespoon prepared horseradish, drained
1 Tablespoon spicy brown mustard
1/8 teaspoon salt
1/8 teaspoon black pepper
2 cups lightly packed trimmed watercress
8 slices high fiber bread
1/2 pound very thinly sliced deli roast beef
1 large tomato, thinly sliced

1. Combine the sour cream, horseradish, mustard, salt and pepper in a small bowl; set aside.
2. Place the watercress on 4 slices of bread. Top evenly with the roast beef and tomato. Spread the horseradish mixture evenly on the remaining 4 slices of bread; cover the sandwiches with the bread. Cut the sandwiches in half.