Place the steak in a large baking sheet and squeeze lime juice over the steak.
In a small bowl, combine the chili powder, cumin, paprika, garlic powder, salt, pepper, and coriander.
Add the spice rub to the steak, turning to coat the meat thoroughly with the rub and pressing with your fingers to help the rub stick to the meat. If you have time, cover the steak with plastic wrap and keep in the fridge for 30 minutes to 1 hour. You can let it marinate for up to 4 hours.
When ready to grill, preheat a clean, oiled grill to medium-high heat.
Place the steak on the hot grill and grill for 4 to 5 minutes on each side, depending on your preference. The steak should be 130-135°F for medium rare, and 145°F for medium.
Transfer the steak to a large cutting board and cover it loosely with aluminum foil. Let the steak rest for 10 minutes. Cut the steak against the grain into thin slices.
To assemble the salad, place the mixed greens on a large platter. Add the steak, corn, tomatoes, avocado, red onion, pepitas, and queso fresco. Drizzle with desired amount of dressing. Serve immediately.