Preheat the oven to 425°F (220°C) and line a large baking sheet or leave unlined if preferred.
In a mixing bowl, combine the chili powder, cumin, smoked paprika, garlic powder, kosher salt and pepper, and 2 tablespoons of the olive oil.
Add the chicken strips to the spice mixture and toss until evenly coated; arrange the chicken in an even layer on one side of the baking sheet.
On the other side of the sheet, toss the sliced orange and red bell peppers, sliced poblano, and thinly sliced sweet onion with the remaining 1 tablespoon olive oil and a pinch of salt and pepper.
Bake the sheet pan for 20–35 minutes, until the chicken is cooked through (no pink inside) and the peppers begin to char, stirring once halfway through if needed.
Remove the pan from the oven and toss the chicken and vegetables together with the juice of 1 lime and the chopped cilantro.
To serve, divide steamed rice among warmed flour tortillas, top with the chicken and pepper mixture, then add shredded cheddar, sliced avocado, extra cilantro, a squeeze of lime, and salsa as desired.