Wash hands. Slice bread loaf in half lengthwise, then cut the bread into quarters. Place in a covered storage container, label, date, and store until needed.
Wash all fresh, unpackaged produce under running water. Drain well. Generously brush olive oil on both sides of bread, allowing oil to soak into the bread. Press bread on a grill, or heated griddle with weight placed on the bread to flatten it. Place bread on a heated serving plate. Sprinkle onions and warmed chicken tinga on top of the bread. Sprinkle green chilies, lettuce, and tomatoes on top of the chicken. Drizzle sour cream over the top of the chicken. Sprinkle the cheese and cilantro on top of the sour cream and serve.