For the leek frittata, preheat the oven to 180 °C top and bottom heat. Cut the leeks into slices and wash them thoroughly.
Heat olive oil in a pan and sauté the leeks in it. Add salt, eggs, mix with the leeks and fry briefly.
Put the pan in the hot oven and bake until the eggs are set (5-10 minutes). In the meantime, put the ingredients for the ketchup in a bowl, blend finely with a blender and season with salt if necessary.
Slide the finished frittata onto a plate and serve with the ketchup.