1) If using regular yoghurt, place it in a strainer lined with paper towel and set the strainer over a bowl. Let the yoghurt drain and thicken for 20 minutes.
2) Combine thickened or Greek-style yoghurt, mayonnaise, horseradish and salt and pepper in a small bowl and stir to incorporate.
3) Place a small amount of watercress on four slices of bread and drizzle with two tablespoons of horseradish mayonnaise. Layer with 85g of roast beef per sandwich, tomato slices and onion slices.
4) Top with another slice of bread and wrap in waxed paper, then aluminum foil.
Calories 330; Total Fat 9 g; (Sat Fat 2 g, Mono Fat 2 g, Poly Fat 4 g) ; Protein 22 g; Carb 40 g; Fiber 6 g; Cholesterol 33 mg; Sodium 1300 mg
Excellent source of: Protein, Fiber, Vitamin C, Vitamin K, Manganese, Selenium
Good source of: Vitamin A, Thiamin, Riboflavin, Niacin, Folate, Calcium, Copper, Iron, Magnesium, Phosphorus