Cut cucumber or Kheera into fine cubes.
Now heat oil in a wok or kadai. When oil is hot simmer flame and add mustard seeds. When they begin to splutter. Add jeera powder, turmeric powder, dhania powder, red chilli powder, black salt, and fenugreek powder and Hing.
Now add kalonji or onion seeds and sugar.
Now add the cucumber pieces and saute for a few minutes. Then switch off the flame.
When the cucumber mixture is brought to room temperature. Add lemon juice or white vinegar. Store in a glass jar. Cucumber /Kheera/Vellarkkai pickle is now ready.