Rub U.S. turkey breast with salt and pepper.
Place in a roasting pan.
Cover with aluminum foil and let stand for 15 minutes.
Roast for an hour or until cooked through to desired doneness.
Cut into slices.
Mix lettuce with cucumber, avocado, lemon juice and olive oil in a large salad bowl.
Add breast slices and toss lightly.
Sprinkle with mustard powder and serve.