Remove the outer leaves and extended stem from the head of cauliflower. Working from the center, slice across the entire head to create 4 steaks. Steaks can only be made with the florets attached to the core stem. (Florets that detach from the core can be cooked on the side or reserved for another meal.)
Heat a grill or grill pan to medium-high heat. Coat each side of the cauliflower steaks with olive oil, a sprinkle of kosher salt, and fresh ground pepper. Grill each side for 3 to 4 minutes until lightly charred.
For the fresh salsa, cut off the corn, enough for 2 cups kernels. Cut the cherry tomatoes into quarters. Drain and rinse the black beans. Chop the cilantro. Juice 2 limes.
In a medium bowl, mix together corn, tomatoes, black beans, cilantro, lime juice, taco seasoning, 1 pinch kosher salt, 1 tablespoon olive oil,and fresh ground pepper. Stir to combine; taste, and add additional seasonings if desired.
To serve, place each steak on a plate, and spoon over mounds of fresh salsa.