In large pot, boil chicken breasts with one sliced bell pepper, one sliced onion, and a sprig or two of cilantro until fully cooked.
While chicken is boiling, heat oil in deep fryer or pot to 350° (medium low heat on stove). Add one tortilla to oil, pressing down on the center of the tortilla with a ladle or wooden spoon to form "bowl" shape. Fry for about 30 seconds or until light golden brown. Remove to paper towel to dry. Repeat until all tortillas have been fried.
Shred chicken.
In a frying pan, brown chorizo. When fully cooked, drain fat. Add refried beans and stir well. Reduce heat to lowest setting to keep warm.
Chop toppings and place in serving bowls.
To make tostadas, first place a layer of chorizo bean mixture on the tortilla, then add shredded chicken. Top with desired additional toppings.