2Preheat your oven to 375°F (190°C).
Peel and thinly slice the potatoes.
Heat 1 tablespoon of olive oil in a large oven-safe skillet over medium heat.
Add the sliced potatoes to the skillet and cook for about 10 minutes, stirring occasionally, until they are tender and slightly golden.
While the potatoes are cooking, dice the onion and tomato.
In a bowl, beat the eggs with the salt and black pepper.
Once the potatoes are cooked, remove them from the skillet and set aside.
Add the remaining 1 tablespoon of olive oil to the skillet and sauté the diced onion until it becomes translucent.
Add the diced tomato to the skillet and cook for another 2-3 minutes.
Return the cooked potatoes to the skillet, spreading them evenly.
Pour the beaten eggs over the vegetables in the skillet.
Cook on the stovetop for about 5 minutes, until the edges start to set.
Transfer the skillet to the preheated oven and bake for 10-15 minutes, or until the frittata is fully set and slightly golden on top.
Remove from the oven and let it cool for a few minutes before slicing and serving.