Set the Instant Pot in saute mode and add the oil.
When the oil is hot, add the mustard seeds and hing. Let the mustard seeds splutter.
Now add the onion, mint leaves, and curry leaves. Saute it for five minutes.
Turn off the Instant Pot and add the tomatoes, salt, and red chili powder.
Gently mix and add the jaggery and sprinkle two tbsps of water on top.
Close the Instant Pot lid and make the vent is in the sealing position. Pressure cook this for 5 minutes at high pressure and let the pressure release naturally when the cooking is complete.
After the pressure is all released, open the Instant Pot and set it back in saute mode.
Mix and mash the tomatoes, and by now, the consistency will be thin, and it's normal. Check for salt and spice and, if required, adjust accordingly. If the relish is spicy, add salt and jaggery to balance it. For us, the spice measure, as mentioned above, was perfect.
Now partially cover the Instant Pot with its lid or any other lid and let it simmer in saute mode for 20 to 25 minutes. Stir in between for every 5 to 7 minutes.
Turn off the Instant Pot after 25 minutes and let it cool for an hour. As the relish cools, it thickens, and here is mine after complete cooling.
And don't worry about relish getting stuck to the bottom of the pan. Look below. It comes out clean.
Now store it in an air-tight bottle and refrigerate. It stays wells for 10 to 15 days.
Pressure Cooker Method-
You can make this recipe in a stove-top pressure cooker as well. In a pressure pan or cooker, add oil and when the oil hot add the mustard seeds and hing. Let it splutter and add the onion, mint leaves, and curry leaves. Saute for 5 to 7 minutes, then add the tomatoes, red chili powder, salt, jaggery, and water. Pressure cook for two whistles and let the pressure subside. Then mix and mash the tomatoes and onion. Check for the seasoning and let it simmer over medium heat till it thickens to a semi-solid stage.
While this dish is vegan, it is not gluten-free. A generous pinch of asafoetida enhances the flavor of this dish. So I would not skip that, and you can always opt for gluten-free asafoetida.
I have added a lot of mustard seeds. It's an excellent natural preservative. If you don't like the bite, you can reduce the amount and add mustard powder instead.
Adjust the salt, red chili powder, and jaggery according to your preference and also according to the sourness of the tomatoes. Jaggery is optional. You can keep the relish completely spicy if you like to.
I did not add any tamarind, but if your tomatoes are not sour, you can add a ½ to tsp of tamarind paste. If you like spicy and sour relish, feel free to add ½ tsp of tamarind paste.
I like the subtle flavor of mint, so I always mint leaves. But that's completely optional. Skip curry leaves if you can't find it.