Chicken Fajitas

1 small onion, thinly sliced
juice of two limes
2 cloves garlic, minced
1/2 teaspoon oregano
1/2 teaspoon chili powder
1/2 teaspoon ground cumin
1/2 teaspoon coarsely ground pepper

1 pound boneless chicken brests, cut into thin strips
1/2 medium green pepper, cut into 2x14-inch strips
1/2 medium red bell pepper, cut into 2x14-inch strips
4-6 flour tortillas (8-inch), warm
1 medium tomato, chopped
sour cream

Place onion in crockette. Combine lime juice and seasonings in small bowl. Add chicken and toss to coat. Pour chicken and juice mixture over onion. Cover and cook 6-8 hours. Stir in green and red pepper strips 30 minutes before serving.
Serve on warmed Tortillas, topped with tomato and sour cream.