Cut the chicken into bite-sized chunks and season with ½ teaspoon kosher salt. Set aside.
Add butter or oil to the Instant Pot, set to sauté, and heat. Add onion, garlic, ginger, garam masala, cayenne, cumin, black pepper and turmeric.
Cook, stirring frequently, until onion is soft and the mixture is very fragrant.
Add tomato paste and cook 1 more minute, stirring until well combined.
Add chicken and sauté until just browned, about 4 to 5 minutes.
Add tomato puree. Open the cans of coconut milk, carefully spoon out the thick cream, and set it aside.
Add ¾ cup of the thinner, watery "milk" from the coconut milk to the Instant Pot, along with the remaining salt.
Cover and cook on high pressure for 10 minutes, then quick-release.
Uncover and stir in the reserved coconut cream and cauliflower florets. Turn the Instant Pot to sauté and simmer until thickened, about 15 minutes.
Stir in the yogurt and lemon juice just before serving. Serve over cauliflower rice or Perfect Basmati Rice.