In a large skillet over medium heat, brown the ground beef or turkey with the chopped onion until fully cooked, then drain any excess fat; stir in the taco seasoning and a splash of water, reduce heat to low, and cook for 2–3 minutes, stirring occasionally until well combined. Meanwhile, cook the rice according to package directions, then stir in the salt, a squeeze of lime juice, and optional cilantro. Heat the corn on the stovetop or in the microwave (or prepare it street-corn style if you’re feeling bold). To assemble, layer the bowl as desired—rice, seasoned meat, corn, beans, and then your preferred toppings like lettuce, tomatoes or pico, cheese, sour cream or Greek yogurt, avocado or guacamole, jalapeños, and salsa or hot sauce—and serve immediately.