Mediterranean Roast Beef Pita

3 tablespoons pine nuts
1/2 pound deli roast beef, cut into thin strips
2 cups shredded romaine lettuce
1 cup shredded carrots
1 cup thinly sliced cucumber
1/2 cup thinly sliced red onion
1/3 cup crumbled feta
4 whole-wheat pita pockets
2 tablespoons fat-free mayonnaise
2 tablespoons skim milk
1 tablespoon cider vinegar

Toast pine nuts: Place in a dry small skillet over medium heat; stir occasionally until lightly browned, about 3 minutes. Cool. Toss nuts, beef, lettuce, carrots, cucumber, onion and feta in a bowl. Slice off 1/4 of each pita; stuff larger piece with filling. Whisk mayonnaise, milk and vinegar in another bowl. Drizzle dressing over pita filling. Serve with remaining 1/4 pita.