In a medium bowl, mix chili powder, garlic powder, paprika, and Kosher salt together.
In another bowl, add half of the spice mixture along with the venison strips and 2 tablespoons of olive oil. Massage spice mixture into the venison. Cover the venison and allow to marinate for 12 hours, or overnight.
Preheat oven to 425° F. On a large baking sheet, add peppers, onion and corn and drizzle remaining 2 tablespoons of olive oil, along with the remaining spice mixture over the vegetables and toss to combine. Transfer the vegetables to the oven and cook for 12 minutes.
Remove the vegetables from the oven and scoot the vegetables to one side of the pan. Place the venison in an even layer onto the other side of the pan. Transfer the sheet pan to the oven and bake for another 10 minutes or until the venison is cooked and the peppers are beginning to char.
Remove from the oven and toss the vegetables and venison with the cilantro and lime juice.
To serve, divide the ingredients among the warmed tortillas and top with avocado slices, cheese, cilantro, and sour cream.