Chop onions into 1/4 inch pieces, mince garlic, chop pepper into 1/4 inch pieces. Chop tomatoes or use canned tomatoes.
Remove skin from chicken and cut into 1 inch cubes. Combine all ingredients except lime juice, tosadas, and cilantro. Bring to a boil and cook for 20 minutes. Reduce heat to low, cover and simmer for 2 hours. Stir in lime juice right before serving. Break the tostadas into small pieces. Sprinkle soup with tostadas and cilantro before serving.