1	lb. lean ground beef
4	plum tomatoes, cut into thin slices
8	small pita pocket breads (4-inch diameter), cut in half, warmed
	Seasoning
1	clove garlic, crushed
1/2	tsp. salt
1/2	tsp. dried oregano leaves
1/4	tsp. pepper
	Yogurt Sauce
2/3	cup plain low-fat yogurt
1/3	cup chopped cucumber
3	Tbsp. finely chopped onion
2	tsp. chopped fresh parsley