Using the sauté function, add the coconut oil. When the oil is hot, add the mustard seeds and curry leaves.
When the mustard seeds start popping, add all the rest of the ingredients except the salt and lemon juice. Place the lid on, close the pressure valve, and change the instant pot setting to pressure cook on high for 10 minutes.
When the Instant Pot beeps, let the pressure release naturally (NPR) for 10 minutes. Then release the pressure manually, open the lid when the pot is ready. Add the salt and lemon juice if using.
For a rich flourish just before serving, drizzle a bit of ghee over the top.
Cooking on the Stovetop
Drain the water and return the dal to the saucepan. Add 4 cups of water, a small Indian green chili, and bring to a boil. Simmer over medium-high heat until the peas are just tender, but not mushy. This will take about 15 minutes.
In another pan on medium, heat the coconut oil and add the mustard seeds and curry leaves. When the mustard seeds start popping, after about 2 minutes, add the other Indian green chili, the cumin, and turmeric. Sauté for a minute or two to toast the spices. Add the coconut milk and simmer on low for 3 to 5 minutes. Remove from the heat until the dal is finished cooking.
Drain the dal and mix it into the coconut milk and spice mixture. Add the salt and lemon juice and taste for acid and salt. If you want more chili heat, add a pinch or two of Kashmiri ground chili. Drizzle with ghee if you wish before serving.
Depending on the lentils you are using, you may need to tweak the salt and lemon juice (if using).
I have cooked with three different dals (lentils) for this coconut lentil soup, and they all are delicious. I do encourage you to find the toor dal, however.
You may find the finished dal too thick for your taste. Simply add water until you have the desired consistency.
If you prefer lentils that keep their shape rather than dissolve into the soup, cook the dal on high pressure for 8 minutes rather than 10, if you are using the Instant Pot. If you are cooking on the stovetop, you can start checking your lentils at the 10-minute mark.
This is a mild dish. If you prefer more heat and possibly a more intensely flavored dal, rather than leaving the chilis whole mince them. Also, feel free to add another chili or so. Starting with a 1/4 teaspoon of Kashmiri chili powder, up the heat at the end if you feel the dish needs it. You can also add a teaspoon or more of minced or grated garlic with the rest of the ingredients if you are using the Instant Pot. If you are cooking on the stovetop, add a clove or two of crushed garlic in as the dal is cooking.