For the pancakes, grate potatoes and onion finley and mix together. Place the grated potato and onion into a colander and squeeze out as much moisture as you can. Or roll up the potato and onion in a clean kitchen tea towel and wring well to extract the liquid. Mix the potato and onion with the flour, egg and salt and freshly ground pepper.Heat the oil in a frying pan until moderately hot and then place heaped tablespoons of the mixture into the pan to shallow-fry. Lower the heat to medium, flatten each latke with the back of a spoon and fry for about five minutes on each side, turning over when the edges turn golden-brown. If the heat is too high, the latkes will become dark-brown on the outside before they are cooked inside.
Preheat oven at 200 ° C. Cut mozzarella into small pieces, rocket coarsely.
Place potato pancake on a plate and sprinkle with mozzarella. Season with salt and pepper and bake for 8 minutes in oven.
Cover pancakes with rocket salad and ham, garnish with capers and drizzle with olive oil and vinegar.

Tip: If time is short, use frozen potato pancakes.