Partly slit the chillies at the tail and keep aside. Scrape the skin off the ginger, chop fine and keep aside. Roast the fenugreek seeds until they turn dark brown, grind into a fine powder and keep aside. Cook the lemons with turmeric powder in a little water, drain, chop each of them into 8 pieces and keep aside. Ensure that the chopped lemons are seeded so that the shelf-life of the pickle is not affected. Saute well the green chillies in a little oil and add to the lemon pieces. Add ginger also and mix well with green chillies and lemon pieces. Add powdered fenugreek seeds, asafoetida powder and salt to taste, mix well. Season with mustard and serve.