In a small bowl, mix together chili powder, garlic powder, cinnamon, cumin, and salt until well combined. Rub the mixture over the skirt steak and let it sit for at least 15 minutes.

Preheat your grill to medium-high heat, about 400°F (200°C). Grill the seasoned skirt steak for 3-5 minutes on each side until charred and cooked to desired doneness. Remove from grill, cover with foil, and let rest for 10 minutes.

Grill the ear of corn, turning every few minutes until it's charred and tender, roughly 10-15 minutes.

In a mixing bowl, combine diced cucumber, kernels from the grilled corn, diced jalapeño, and diced red onion. Squeeze lime juice over the mixture and add salt to taste. Stir to combine.

Slice the rested steak thinly against the grain. Take a warm corn tortilla, add steak slices, top with salsa, cilantro, and avocado if desired. Fold and serve.