Place the turkey bacon in a cold non-stick skillet and turn the heat to medium, cooking until the edges are browned and the bacon is fully cooked.
Remove the bacon from the pan, chop into small pieces, and set aside.
In the same skillet, add the spinach and a splash of water, sautéing for 1-2 minutes until just wilted, then remove and set aside.
Wipe the skillet clean and add the avocado oil, heating over medium-high heat until the oil is shimmering.
Whisk the egg whites until slightly frothy and pour them into the hot skillet, letting the edges set and become golden and crisp.
Once the center of the egg whites is nearly set, place the cooked turkey bacon and spinach on one half of the omelette.
Carefully fold the other half over the filling and cook for another 30 seconds.
Slide the omelette onto a plate and serve immediately with sliced avocado on the side.