Set the Instant Pot® on Sauté mode and heat the oil. When hot, add the onion and sauté lightly for about 5 minutes. Add the cashews and raisins and cook for another minute or so. Stir in the mint powder, Basic Makhani Masala, and 1/4 cup of water. Press Cancel to turn off Sauté mode. Transfer the sauce to a bowl.
Carefully remove the cauliflower from its outer leaves in a single piece. Place the whole cauliflower in the Instant Pot®. Spoon the prepared sauce over the cauliflower. Close the lid and set the Instant Pot® on Manual Low Pressure mode for 3 minutes.
When the cooking time is complete, allow for a Natural Pressure Release for 5 minutes.
Once the pressure is released, carefully remove the whole cauliflower without breaking it and place it on a serving tray or bowl. Spoon all the cooking sauce over the cauliflower. Sprinkle with lemon juice and garnish with chopped cilantro and mint.
If you don't want to make your own Makhani Masala sauce, you can find prepared versions, but note they will probably include butter and will therefore not be vegan. Prepared sauces are usually high in sodium too.