Peel and finely chop the onion. Whisk the eggs and season with salt. Wash and peel the potatoes and slice or roughly grate them. Heat oil in a pan (20 cm Ø). Brown the ham briefly in it. Add the potatoes, fry for 1-2 minutes while turning, season with pepper. Push together to form a Rösti.
Sprinkle cheese over it and pour eggs over it. Cover and cook over low heat for 6-8 minutes. When the underside is browned and the egg has set, turn with a flat pan lid. Slide back into the pan and fry for another 4-5 minutes. Wash the chives, dab dry and cut into small rolls. Sprinkle Rösti with it. Serve with gherkins