Soak the red cow peas in hot water for about half an hour. Drain the water. Add just enough water to cover the cow peas and pressure cook till soft, but not mushy. Drain and keep aside the water and cooked cow peas separately.
Grind the fresh coconut, cumin seeds and the red chillies together with a little water into a reasonably thick and smooth paste. Use just one chilli if you prefer a less spicy curry. Keep aside.
Put the diced jackfruit (about 1/2″ squares) with turmeric and a little salt in a medium to large pot. Add about a little over a cup of water. You can use the water drained from the cooking the cow peas for this.
Stir and bring to a boil. Turn down the heat, and let it simmer, stirring to make sure it doesn’t stick to the bottom of the pot. Add a little more water, if necessary. The jackfruit should cook quickly. It should be soft but not mushy.
At this point there should be very little water in the cooked jackfruit pieces. Stir in the cooked cow peas. Cook for about 5 minutes. Stir in the coconut-cumin paste. Add more salt as required. Cook for another 3 to 4 minutes until the curry comes to a boil. Stir well and take it off the heat.
Put the fresh coconut for the tempering in a smallish sauté pan. Toast over medium heat, stirring frequently, until it turns gives an aroma and turns golden brown in colour. Transfer to the top of the cooked jackfruit.
In the same pan, heat the coconut oil. Add the mustard seeds. When they splutter add the lentils and sauté till they start turning golden brown. Stir in the chillies and the curry leaves. Immediately pour this into the curry over the toasted coconut. Serve warm. Just before serving, mix the toasted coconut and the rest of the tempering.