Beef Gyros with Tzatziki Sauce

Prepare Tzatziki Sauce: In a small bowl stir together Greek yogurt, cucumber, red wine vinegar, dill, minced garlic and salt. Cover and chill up to 4 hours until ready to serve.

Prepare Beef Gyros: Preheat oven to 325 degrees F. Line a 9x5-inch loaf pan with parchment paper; coat paper with cooking spray.

In a food processor combine the 1 cup onion and the water; cover and process until smooth. Press pureed onion through a fine-mesh sieve to remove excess liquid; discard liquid. Return onion to food processor. Add the ground beef, egg, bread crumbs, oregano, marjoram, garlic, salt and pepper). Cover and process until mixture forms a paste.

Lightly press meat mixture into prepared loaf pan. Place loaf pan in a 13x9-inch baking pan. Pour enough boiling water into baking pan to reach halfway up sides of loaf pan. Bake 35 to 40 minutes or until done (160 degrees F) (see Tip). Drain off fat. Cool 10 minutes. Remove; cut into slices about 1/4-inch thick.

Fill pita bread with meat, tomato, cucumber and red onion slices; top with cheese. Serve with Tzatziki Sauce.