Peel onions and cut 1 1/2 onions into 36 thin slices, dice remaining onion. Dice 75 g of gherkins as well. Wash and quarter the apple and cut out the core.
Cut the apple into small pieces. Wash the herbs, dab dry and cut finely, except for some dill for garnishing. Mix sour cream, yoghurt, diced onion and chopped herbs. Add cucumber cubes and apple and season with salt, pepper and possibly some cucumber water.
Put the sauce aside. Wash the maties, dab dry with kitchen paper and cut the fillets lengthwise, slightly diagonally in half. Cut the remaining gherkins into 48 sticks. Place an onion wedge and 2 gherkin sticks on each strip of matie, roll up and place 2 rolls on a shish kebab.
Put the finished skewers (12 pieces) in a cool place. Peel and wash the potatoes and cut them into thick sticks. Wrap potatoes briefly in a cloth (they are then drier and do not splash when soaked in hot oil).
Heat the oil in a pot and fry/pre-cook the potatoes in portions for approx. 8 minutes. Let them drip off on kitchen paper. Just before serving, fry the potatoes for another 4-6 minutes until they are brown.
Also drain and sprinkle with salt. Arrange the matie skewers with the sauce on plates. Garnish with lemon and dill and serve with French fries.