In a high-speed blender, process all ingredients until smooth. Alternatively, use a stick blender with a container.
red potatoes, cut into medium cubes
In a pot of boiling water, cook red potatoes until tender. Drain.
Preheat oven to 200℃ / 390℉.
In a pan over low-medium heat, cook onion in half tablespoon of olive oil until soft and transparent.
Add red potatoes, sea salt, and remaining olive oil. Stir to coat well until lightly golden.
Stir in the batter with the ingredients.
Grease an 8" oven-proof pan and line with parchment paper.
Pour the mixture in and press down with spatula until flat. Bake until a skewer inserted into the center comes out clean (30m). Remove from oven.
Let it rest for 10m to firm up.
Cut omelette into four portions. Serve each person with a plate, starting with one portion of omelette each.