This pickle is based on my Nani’s basic quick achar recipe-use it to create your own pickles by changing the vegetables and flavourings. Split mustard seeds can be bought in Asian shops, but you can make your own by grinding brown mustard seeds with a pestle and mortar. For the tamarind, it’s best to use a dried block, rehydrating it and then sieving the pulp, but you could use ready-made tamarind concentrate if you’re short of time.