Preheat the oven to 200°C.
Peel the potatoes. Cut the in half and then into 1 cm thick slices.
Spread the potatoes on a sheet pan and drizzle with olive oil. Generously sprinkle with sea salt. Bake for 30 to 40 minutes*.
Peel and dice the onion.
Wash the leek. Cut it in half and thinly slice it.
Cover the bottom of a large pan with olive oil. When hot, sauté the onion until translucent. Add in the leek and stir-fry over medium-high heat until it caramelizes (10 to 15 minutes). Watch carefully and stir regularly to avoid burning. Take away from the heat source when caramelized (see post above for step-by-step pictures).
Break the eggs in a bowl and whisk with a fork.
Check if the potatoes are already soft with a fork. If yes, add the to a non-stick roasting pan or oven-proof dish. Add the vegetables and the beaten eggs. Give it a stir. Bake for 15 to 20 minutes at 200°C**. It is done when a tester comes out clean.