1 lb. ground beef
1/2 c. onion, chopped
1 tbsp. chili powder
1 tsp. salt
1/4 tsp. oregano
1 can (30 oz.) Rosarita spicy refried beans
1 can (16 oz.) stewed tomatoes
1 1/2 c. shredded Monterey Jack cheese
1 1/2 c. tortilla chips
1 c. sour cream, optional