Directions

1. 1Peel the potatoes and cut into small pieces (about 1 cm cubes). Finely chop the onion and chop the rosemary.
2. 2Sauté the onion, bacon, and rosemary with olive oil in a large pan that can go in the oven. When the onions are glossy (not brown!), add the potato cubes, briefly sauté, then reduce heat and gently simmer. Stir frequently. It takes about 10 to 15 minutes, then the potatoes are fork-tender.
3. 3Preheat the oven to about 160 degrees Celsius.
4. 4Meanwhile, cut the tomatoes into small pieces. Beat the eggs in a large bowl with salt and pepper. Add about 4 tablespoons of warm water and beat again. When the potatoes are fork-tender, add the tomatoes to the pan and briefly sauté.
5. 5Take the pan with the potato mixture from the heat and transfer the contents into a bowl. Stir to ensure all potatoes are covered with egg mixture. Add another egg if needed. Let the mixture stand for about 5 minutes. Meanwhile, wash the pan and heat it again with a little olive oil. This helps prevent any residue from sticking to the bottom of the pan - otherwise there's a risk the tortilla will stick to the pan bottom.
6. 6After about 5 minutes, when the oil in the pan is hot, add the mixture to the pan (caution, it can splatter!) and cook over medium heat until it starts to set. The edges should stick slightly - this takes about 5 minutes. Now the pan can go in the oven. It stays there for about 30 minutes - checking occasionally. The goal is that the entire egg mixture is set and the surface is not too dark. Otherwise cover with aluminum foil.
7. 7Remove the pan from the oven, turn it onto a large plate and serve.