Start by turning the Instant Pot® to sauté and add hamburger, or ground turkey. Cook until brown. Next add your water, taco seasoning, rice, corn, and black beans, and stir until well combined and rice is covered with the water added. Turn the pressure valve to sealing and pressure cook on High, for 9 minutes. Let it pressure release naturally for about 13 minutes, then turn to quick release. GENTLY fluff your rice. Place the lid back on and turn the Instant Pot off until ready to serve. Lay the lettuce leaves out on some salad size plates when ready to serve, and top with rice and hamburger mixture. Add cheese, salsa, and onions. Top with sour cream, if desired. Serve and Enjoy!