Beef Canapes with Cucumber Sauce

4 cups (32 ounces) plain yogurt
1 beef tenderloin roast (1-1/2 pounds)
2 tablespoons olive oil, divided
1 teaspoon salt, divided
1/4 teaspoon plus 1/8 teaspoon white pepper, divided
1 medium cucumber, peeled, seeded and diced
1 tablespoon finely chopped onion
1 garlic clove, minced
1 tablespoon white vinegar
1 French bread baguette (1 pound), cut into 36 thin slices
1 cup fresh arugula
Sliced grape tomatoes, optional

Line a fine mesh strainer with two layers of cheesecloth; place over a bowl. Place yogurt in strainer. Cover and refrigerate for at least 4 hours or overnight. Rub tenderloin with 1 tablespoon oil. Sprinkle with 1/2 teaspoon salt and 1/4 teaspoon white pepper. In a large skillet, cook tenderloin over medium-high heat until browned on all sides. Transfer to a shallow roasting pan. Bake at 400° for 25-30 minutes or until a thermometer reads 145°. Cool on a wire rack for 1 hour. Cover and refrigerate.

Transfer yogurt from strainer to another bowl (discard yogurt liquid). Add the cucumber, onion, garlic and remaining salt and white pepper. In a small bowl, whisk the vinegar and remaining oil; stir into yogurt mixture. Thinly slice the tenderloin. Spread yogurt mixture over bread slices; top with beef, arugula and tomato slices if desired. Serve immediately or cover and refrigerate until serving. Make 3 dozen.