Open the can of jackfruit and drain and rinse the fruit in a strainer. Place on a kitchen towel and fold the towel in half to cover the fruit. Press, using the heel of your palm, the jackfruit until it smashes and a lot of the liquid is absorbed into the towel. Separate the soft jackfruit from the hard core and discard the inedible core and large seeds.
Add all of the marinade ingredients to the jackfruit and stir well to coat. Set aside for at least 20 minutes.
In a medium heavy bottom pot or dutch oven, melt the 3 tbsp of vegan butter over medium heat until it just begins to foam. At this point, add the red onion and cook for about 5 – 10 minutes or until it begins to brown and caramelize.
Add the chopped tomatoes, water, cashews, salt, vinegar, sugar, and chili powder. Stir well, bring up to a simmer, then reduce the heat to low and cook for 20 – 25 minutes.
After the sauce has cooked down, add it to a high powered blender and blend on high for 60 seconds or until completely smooth. Add back into the pan and return to a low heat. Alternatively, if you have a lower powered blender, strain the mixture before adding back into the pan.
Add in the marinated jackfruit at this point and allow it to simmer in the sauce for about 20 – 30 minutes to soften the jackfruit and let the flavours mingle and come together. Stir occasionally so it does not burn on the bottom.
While the jackfruit simmers in the sauce, start your rice if serving and/or begin cooking naan.
Taste the curry and adjust sugar, salt, or vinegar levels before serving. Sprinkle kasoori methi over the sauce and serve alongside basmati rice, naan, and fresh cilantro if desired.