Place all bread ingredients in a bowl. Whisk together until they are homogeneous and smooth. Pour batter into muffin cup or small baking pan. Microwave for 90 seconds. Transfer to a cutting board to cool for one minute and a half before cutting into slices.
Making the Fillings
Prepare the boiled chicken breast and shred it. Pour the oil into a hot frying pan. Throw in the chicken pieces and sauté with onion. Add a decent amount of salt and pepper to flavor. Allow cooking for 10 minutes.
Mash the avocado in a small bowl.
Lay the bread on a plate. Spread the mashed avocado on one piece and the cooked chicken mix in another. Sandwich the pieces together. Use the same process on the remaining ingredients.