How Oma Leni taught me... if they are small, just leave whole, otherwise slice. Simmer in boiling, salted, water until slightly soft (not too soft, otherwise they go mushy). You need quite a good handful of salt, not just a measly teaspoon. Slice a large onion and put it in a bowl. Add the drained gherkins or sliced cucumber (they have to be on top of the onions but I can't remember why). Reserve the cooking water. Add some peppercorns and lots of dill (to taste) and a couple of bayleaves. Pour on the drained cooking water (it should still be boiling, however). Cover with a tight lid and leave overnight. Then drain and store in the fridge. This actually tastes much better than pickled with vinegar (although will not keep as long). It is an old recipe from Russia (she was from Schlesien and learnt it from her Grandmother, who was from somewhere remote in the vast depths of Imperial Russia).