In a small cup, whisk together the egg, water, and salt and pepper. Pour in to a pre-heated small non-stick skillet and cook 2 - 3 minutes over medium heat until most of the egg is set.

Flip omelet over and top with shredded cheese. Cook 1 minute more until egg is cooked through.

Fold omelet to fit on the roll. Top with bacon, avocado and tomato slices and additional salt and pepper if desired.