Peel the onions. Peel cucumbers, cut them lengthwise in half and remove seeds. Weigh 1 kg. Cut onions and cucumbers into very small cubes.
Mix onions, gherkins, vinegar, sugar, mustard seeds and salt in a large pot. Season with 1 teaspoon of pepper. Bring to the boil and simmer at high heat for about 12 minutes.
Meanwhile, wash the dill, shake dry, pluck the pennants and cut finely. Add about 3 minutes before the end of the cooking time and cook along with the dill.
Immediately pour Relish into clean twist-off jars, seal and allow to cool. Store in a cool place. Tastes great with grilled and roasted meat or on hamburgers.