Preheat your grill to medium-high heat. If using frozen corn, thaw it and drain any excess water.
In a bowl, combine the corn kernels, olive oil, chili powder, garlic powder, smoked paprika, salt, and pepper. Toss to coat the corn evenly.
Place the seasoned corn on a grill-safe pan or directly on the grill grates. Grill for about 5-7 minutes, stirring occasionally, until the corn is charred and tender. Remove from the grill and set aside.
Season the flank steak with salt, pepper, and lime juice. Grill the steak for about 4-5 minutes per side for medium-rare, or until it reaches your desired doneness. Remove from the grill and let it rest for 5 minutes before slicing thinly against the grain.
While the steak is resting, warm the corn tortillas on the grill for about 30 seconds on each side until pliable.
To assemble the tacos, place a few slices of steak on each tortilla, top with grilled corn, crumbled cotija cheese, chopped cilantro, and avocado slices.
Serve immediately with lime wedges on the side for squeezing over the tacos.