Chicken Tostadas

8 Six inch tostadas shells
2 Cans (16 ounces) refried beans
2 Cups cut-up cooked chicken
1 1/2 Teaspoon chili powder
1 Teaspoon dried oregano leaves
1/2 Teaspoon salt
1/4 Teaspoon ground cumin
1 Can (12 ounce) tomato sauce
1 Medium avocado, sliced
1/4 Teaspoon Lemon juice
1 1/2 Cups shredded lowfat cheddar or Monterey Jack cheese
2 Medium tomatoes, sliced
4 Cups shredded lettuce
1/2 Cup light sour cream
Hot taco sauce
Heat tostada shells as directed on package. Heat beans over medium heat until hot. Heat chicken, chili powder, oregano, salt, cumin, and tomato sauce until hot. Peel and cut avocado lengthwise into slices; sprinkle with lemon juice. Spread about 1/4 cup of the beans on each tostada shell; spread with about 1/4 cup chicken mixture. Sprinkle 2 tablespoons cheese over each. Arrange lettuce, tomato, and avocado slices on top. Serve with sour cream and taco sauce. 8 servings