Preheat the oven to 425°F and lightly spray a rimmed baking sheet with nonstick spray.
In a large bowl, toss the chicken strips with 2 tablespoons olive oil, 1 tablespoon chili powder, 1 teaspoon cumin, 1 teaspoon paprika, and 1 teaspoon garlic powder until evenly coated.
Arrange the seasoned chicken in a single layer on one side of the prepared baking sheet.
Toss the sliced green bell pepper, sliced poblano, and thinly sliced red onion with the remaining 1 tablespoon olive oil, then spread them on the other side of the baking sheet.
Bake the chicken and vegetables for 25 to 35 minutes, until the chicken is cooked through and the peppers begin to brown; then remove the sheet from the oven and gently toss the chicken and veggies together.
Set the oven to broil. Remove husks from the tomatillos and rinse them, then place the tomatillos on a rimmed baking sheet and broil 10 to 15 minutes until browned on top.
Place the broiled tomatillos in a blender or food processor with the garlic cloves, 1/2 cup cilantro, 1/2 cup diced white onion, 1 tablespoon lime juice, 1/4 teaspoon cumin, and 1/2 teaspoon salt; pulse until you reach the desired salsa consistency.
Serve the shredded/tossed chicken and peppers with the salsa verde, warmed flour tortillas, and cooked rice as desired.