Wash and peel potatoes.
Use a mandolin (or you can try to slice as thin) to cut potatoes. I use setting 2.
Cut onion in half and then slice into thin half rings.
Add salt and mix onions and potatoes together.
In a shallow pan, that allows at least 1 ½ inch add olive oil.
Add potato and onion mixture to oil. Add more oil if needed. You want the potatoes to be completely submerged. The goal is not to fry them, but to soften them. This took between 8-12 minutes.
Scoop the potato and onion mixture out with a draining spoon to remove as much oil as possible, let cool.
While it is cooling, make your egg mixture. Combine eggs, heavy cream and salt.
Once the potatoes are cool to touch, add potatoes to egg mixture and mix.
In a skillet, add a little bit of that reserved oil, and a knob of butter.
Once it starts to sizzle, pour the potato and egg mixture. Let it cook so you see the sides start to cook, reduce heat to low-medium, add lid and let cook till the middle has solidified. It will still be runny on top -don't worry.
Once it is fully cooked on the bottom, take the pan over to the sink with a plate large enough to cover the pan. VERY Carefully, put the plate over the pan and quickly flip. You might lose some egg- It's ok!
Then slide the omelette back onto the same pan. Return to stove with lid on. Cook for an additional 5 minutes or until fully cooked.
Transfer to a plate and slice into little triangular slices. Top with additional salt if necessary. Taste first!