How to Make It
Select SAUTÉ setting on a 6-quart programmable pressure multicooker (such as Instant Pot). (Times, instructions, and settings may vary according to cooker brand or model.) Select HIGH temperature setting, and allow to preheat. Add coconut oil, and heat until very hot and fragrant, about 90 seconds. Add ginger, serrano chile, de árbol chile, mustard seeds, fennel seeds, and, if desired, nigella seeds; cook, stirring constantly, until seeds darken, about 1 minute. Stir in mango, orange juice, and salt. Cover cooker with lid, and lock in place. Turn steam release handle to SEALING position.
Select MANUAL setting on HIGH pressure for 10 minutes. (It will take 5 to 15 minutes for cooker to come up to pressure before cooking begins.)
Let pressure release naturally for 10 minutes. Carefully turn steam release handle to VENTING position, and let steam fully escape (float valve will drop). (This will take 5 to 15 minutes.) Remove lid from cooker. Remove and discard chiles.
Select SAUTÉ setting on MEDIUM temperature setting. Add coconut sugar, and cook, gently breaking up large pieces of mango with a wooden spoon, until mixture has thickened, 3 to 4 minutes. (Mango mixture will continue to thicken as it cools.) Remove cooker insert, and cool to room temperature, about 45 minutes. Stir in lime juice, and serve.