First deseed and cut the yellow cucumber into small pieces.
In a pan, warm 1 cup of oil. Keep aside.
In a large bowl , make sure the bowl is completely dry, add cucumber pieces, chilli powder, mustard powder, salt, fenugreek-cumin powder.
Mix with a dry spatula until the pieces are evenly coated with the spices. Then add warm oil. Toss everything together.
For tempering, in a pan, add 1 Tbsp of oil , split black gram, mustard seeds, cumin seeds, garlic cloves, red chills and curry leaves. Fry for 2 min and add to the pickle.
Let the pickle cool down completely and store it in air tight container.
Serve it with hot rice and ghee or dosa or idli.