Wash the potatoes and cook in boiling water for about 20 minutes. In the meantime, clean, wash and pat dry the rocket. Roast pine nuts in a pan without fat until golden brown. Peel garlic and chop roughly. Puree the rocket, except for something to garnish, with olive oil, garlic, parmesan and pine nuts in a universal chopper.
Season with salt and pepper. Clean and wash spring onions and cut them diagonally into pieces. Halve the peppers, remove seeds and wash. Cut tuna into cubes. Drain potatoes. Put potatoes, bell peppers, spring onions and tuna alternately on 8 skewers. Sprinkle tuna pieces with sesame seeds. Heat the oil in a pan and fry the skewers for about 5 minutes until golden brown all around. Arrange on plates. Add remaining potatoes and sprinkle with pesto.
Put potatoes, bell peppers, spring onions and tuna alternately on 8 skewers. Sprinkle tuna pieces with sesame seeds. Heat the oil in a pan and fry the skewers for about 5 minutes until golden brown all around. Arrange on plates. Add remaining potatoes and sprinkle with pesto. Garnish with rocket. Add the rest of the pesto