First of all cut all the veggies into medium to big size pieces. Wash it and set aside. In a big pot, boil the water with salt and blanche all the veggies for a couple of minutes. Drain it in the strainer and let it sit there for a few minutes until there is no dripping water out of the strainer.
Then spread the veggies on to a piece of cloth or a sheet and let them dry completely outside in the sun or if the weather doesn't permit then inside. The veggies should be dried completely.
In a big kadai, heat the oil. Add the grated onion and sauté till pink. Add the chopped ginger and garlic and sauté for additional few minutes until the garlic is pinkish too.
Add vinegar and jaggery (Gur) and cook a few minutes more, it will start caramelizing. Do not over overcook it. At this time, add salt, turmeric, red chili powder & paprika. Roast the masala for a few additional minutes.
Turn the gas off. Slightly roast cumin, black peppercorn, mustard seeds and black cardamom and coarsely grind it. Add it to the masala and mix well. Let the masala cool down all the way.
After the veggies are dried, mix the masala with the veggies in a big pot using your hands. Put it out in the sunlight. Let it sit in the pot for a couple of days, mixing a few times during the day. Transfer it to a sterilized airtight glass bottle. Leave it out in the sunlight for a few more days. If for any reason the pickle didn't get enough sunlight then you just put it in the fridge after 3-4 days, so that it doesn't get bad.
Now your achaar is ready. Serve it with a hot paratha, rice & daal, pooris.